#set document(title: "10.5 Chapter Summary and Review", author: "OpenStax / XYZ Homework") #set page(width: 8.5in, height: auto, margin: 1in) #import "@preview/cetz:0.5.2" #set text(font: ("STIX Two Text", "Libertinus Serif", "New Computer Modern"), size: 10.5pt, lang: "en") #show math.equation: set text(font: ("STIX Two Math", "New Computer Modern Math")) #set par(justify: true, leading: 0.62em, spacing: 0.9em) #set enum(spacing: 1.1em) // room between list items so tall inline fractions don't collide #set list(spacing: 1.1em) #set table(stroke: 0.5pt + rgb("#c7ccd3")) #let BLUE = rgb("#183B6F") // brand navy — section bars + example/solution labels (white on navy 11.09:1) #let ORANGE = rgb("#A94509") // brand primary-700 — AA-safe deep orange for TEXT (5.93:1 on white; raw brand #F37021 is 2.94:1 and must never carry text) #let RED = rgb("#DC2626") // brand error-600 #let GREEN = rgb("#059669") // brand success-600 (decoration only; small green text uses green-text #007942) #show heading.where(level: 1): it => block(width: 100%, above: 0pt, below: 16pt, fill: gradient.linear(BLUE, rgb("#2C5AA0")), inset: (x: 14pt, y: 12pt), radius: 3pt, text(fill: white, weight: "bold", size: 19pt, it.body)) #show heading.where(level: 2): it => block(width: 100%, above: 18pt, below: 10pt, fill: BLUE, inset: (x: 10pt, y: 6pt), radius: 2pt, text(fill: white, weight: "bold", size: 12pt, it.body)) #show heading.where(level: 3): it => text(fill: ORANGE, weight: "bold", size: 12.5pt, it.body) #show heading.where(level: 4): it => text(fill: BLUE, weight: "bold", size: 10.5pt, it.body) #let examplebox(label, title, body) = block(width: 100%, breakable: true, fill: rgb("#EFF1F5"), stroke: 0.5pt + rgb("#CFDDF0"), radius: 4pt, inset: 10pt, above: 12pt, below: 12pt)[ #block(below: 6pt)[#box(fill: BLUE, inset: (x: 6pt, y: 2pt), radius: 2pt, text(fill: white, weight: "bold", size: 8.5pt, label)) #h(0.4em) #strong[#title]] #body] // rail = decorative left rule (raw brand token); labelcolor = AA-safe label text shade #let notebox(label, rail, labelcolor, tint, body) = block(width: 100%, breakable: true, fill: tint, stroke: (left: 3pt + rail), inset: (left: 10pt, rest: 8pt), radius: (right: 4pt), above: 11pt, below: 11pt)[ #text(fill: labelcolor, weight: "bold", size: 7.5pt, tracking: 0.5pt)[#upper(label)] #linebreak() #body] #let solutionbox(body) = block(above: 4pt, below: 8pt)[ #text(fill: BLUE, weight: "bold", size: 8.5pt)[Solution] #linebreak() #body] #let figph(msg) = block(width: 100%, height: 60pt, fill: rgb("#f6f7f9"), stroke: (paint: rgb("#c7ccd3"), dash: "dashed"), radius: 4pt, inset: 10pt)[ #align(center + horizon, text(fill: rgb("#889"), style: "italic", size: 9pt, msg))] // Standardize inlined figure sizes: measure the natural CeTZ canvas, then scale to a // consistent envelope (aspect-aware; see build_typst.py FIG_* constants). Unlike the // print preamble, dimensions are FLOORED: in an editor a user can trim a figure to a // degenerate 1-D shape (a bare line), and w/h or tw/w would then divide by zero. #let _STD_W = 3.5 #let _WIDE_W = 5.6 #let _MAX_H = 3.4 #let _ASPECT_WIDE = 2.2 #let _UPSCALE_MAX = 1.15 #let stdfig(body) = context { let m = measure(body) let w = calc.max(m.width / 1in, 0.01) let h = calc.max(m.height / 1in, 0.01) let tw = if w / h > _ASPECT_WIDE { _WIDE_W } else { _STD_W } let s = calc.min(tw / w, _MAX_H / h, _UPSCALE_MAX) align(center, box(scale(x: s * 100%, y: s * 100%, reflow: true, body))) } #show figure: set block(breakable: false) #set figure(gap: 8pt) #show figure.caption: set text(size: 8.5pt, fill: rgb("#555")) == 10.5#h(0.6em)Chapter Summary and Review === Key Concepts + #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[ #emph[Polar Coordinates] The #strong[polar coordinates] of a point #math.equation(block: false, alt: "P")[$P$] in the plane are #math.equation(block: false, alt: "open parenthesis r , θ close parenthesis")[$( r , θ )$], where - #math.equation(block: false, alt: "vertical bar r vertical bar")[$| r |$] is the #strong[distance] from to the pole, - #math.equation(block: false, alt: "θ")[$θ$] is the #strong[angle] measured counterclockwise from the polar axis to the ray through #math.equation(block: false, alt: "P")[$P$] from the pole. #figure(figph[polar], alt: "polar", caption: none) ] + #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[ #emph[Non-Uniqueness of Polar Coordinates] + Any point with polar coordinates #math.equation(block: false, alt: "open parenthesis r , θ close parenthesis")[$( r , θ )$] also has coordinates #math.equation(block: false, alt: "open parenthesis r , θ plus 2 k π close parenthesis")[$( r , θ + 2 k π )$], where #math.equation(block: false, alt: "k")[$k$] is an integer. + The point #math.equation(block: false, alt: "open parenthesis r , θ close parenthesis")[$( r , θ )$] can also be designated by #math.equation(block: false, alt: "open parenthesis minus r , θ plus π close parenthesis")[$( − r , θ + π )$]. + The pole has coordinates #math.equation(block: false, alt: "open parenthesis 0 , θ close parenthesis")[$( 0 , θ )$], for any value of #math.equation(block: false, alt: "θ")[$θ$]. ] + In the polar plane, the coordinate grid lines are circles centered at the pole, with equations #math.equation(block: false, alt: "r equals k")[$r = k$], and lines through the pole, with equations #math.equation(block: false, alt: "θ equals k")[$θ = k$]. + #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[ #emph[Conversion Equations] + To convert from polar coordinates #math.equation(block: false, alt: "open parenthesis r , θ close parenthesis")[$( r , θ )$] to Cartesian: #math.equation(block: true, alt: "x, equals r cos ⁡ open parenthesis θ close parenthesis; y, equals r sin ⁡ open parenthesis θ close parenthesis")[$x & = r cos ( θ ) \ y & = r sin ( θ )$] + To convert from Cartesian coordinates #math.equation(block: false, alt: "open parenthesis x , y close parenthesis")[$( x , y )$] to polar: #math.equation(block: true, alt: "r equals the square root of x squared plus y squared; tan ⁡ open parenthesis θ close parenthesis equals the fraction y over x")[$& r = sqrt(x^(2) + y^(2)) \ & tan ( θ ) = display(frac(y, x))$] where the choice of #math.equation(block: false, alt: "θ")[$θ$] depends on the quadrant. ] + To convert an equation from Cartesian to polar coordinates, we replace each #math.equation(block: false, alt: "x")[$x$] with #math.equation(block: false, alt: "r cos ⁡ open parenthesis θ close parenthesis")[$r cos ( θ )$] and each with #math.equation(block: false, alt: "y")[$y$] with #math.equation(block: false, alt: "r sin close parenthesis")[$r sin \)$]. To convert an equation from polar to Cartesian coordinates, look for expressions of the form #math.equation(block: false, alt: "r cos ⁡ open parenthesis θ close parenthesis , r sin ⁡ open parenthesis θ close parenthesis , r squared")[$r cos ( θ ) , " " r sin ( θ ) , " " r^(2)$], or #math.equation(block: false, alt: "tan ⁡ open parenthesis θ close parenthesis")[$tan ( θ )$]. + When graphing an equation in polar coordinates, we think of sweeping around the pole in the counterclockwise direction, and at each angle #math.equation(block: false, alt: "θ")[$θ$] the #math.equation(block: false, alt: "r")[$r$]-value tells us how far the graph is from the pole. + Standard graphs in polar coordinates include circles and roses, cardioids and limaçons, lemniscates, and spirals. + To find the intersection points of the polar graphs #math.equation(block: false, alt: "r equals f open parenthesis θ close parenthesis")[$r = f ( θ )$] and #math.equation(block: false, alt: "r equals g open parenthesis θ close parenthesis")[$r = g ( θ )$] we solve the equation #math.equation(block: false, alt: "f open parenthesis θ close parenthesis equals g open parenthesis θ close parenthesis")[$f ( θ ) = g ( θ )$]. In addition, we should always check whether the pole is a point on both graphs. + #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[ #emph[Imaginary Unit] We define the imaginary unit, #strong[#math.equation(block: false, alt: "i")[$i$]], by #math.equation(block: true, alt: "i squared equals minus 1 or i equals the square root of minus 1")[$i^(2) = − 1 " " " " " " " " " " " " "or" " " " " " " " " " " " " i = sqrt(− 1)$] ] + The square root of a negative number is an imaginary number: if #math.equation(block: false, alt: "a greater than 0 , the square root of minus a equals i the square root of a")[$a > 0 , " " sqrt(− a) = i sqrt(a)$] + A complex number #math.equation(block: false, alt: "z")[$z$] is the sum of a real number and an imaginary number, #math.equation(block: false, alt: "z equals a plus b i")[$z = a + b i$]. + We can perform the four arithmetic operations on complex numbers. #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[ #emph[Operations on Complex Numbers] #math.equation(block: true, alt: "z sub 1 plus z sub 2 equals open parenthesis a plus b i close parenthesis plus open parenthesis c plus d i close parenthesis equals open parenthesis a plus c close parenthesis plus open parenthesis b plus d close parenthesis i")[$z_(1) + z_(2) = ( a + b i ) + ( c + d i ) = ( a + c ) + ( b + d ) i$]#math.equation(block: true, alt: "z sub 1 minus z sub 2 equals open parenthesis a plus b i close parenthesis minus open parenthesis c plus d i close parenthesis equals open parenthesis a minus c close parenthesis plus open parenthesis b minus d close parenthesis i")[$z_(1) − z_(2) = ( a + b i ) − ( c + d i ) = ( a − c ) + ( b − d ) i$]#math.equation(block: true, alt: "z sub 1 z sub 2 equals open parenthesis a plus b i close parenthesis open parenthesis c plus d i close parenthesis equals open parenthesis a c minus b d close parenthesis plus open parenthesis a d plus b c close parenthesis i")[$z_(1) z_(2) = ( a + b i ) ( c + d i ) = ( a c − b d ) + ( a d + b c ) i$]#math.equation(block: true, alt: "the fraction z sub 1 over z sub 2 equals the fraction a plus b i over c plus d i equals the fraction a plus b i over c plus d i times the fraction c minus d i over c minus d i equals the fraction a c plus b d over c squared plus d squared plus the fraction b c minus a d over c squared plus d squared i")[$display(frac(z_(1), z_(2))) = display(frac(a + b i, c + d i)) = display(frac(a + b i, c + d i)) ⋅ display(frac(c − d i, c − d i)) = display(frac(a c + b d, c^(2) + d^(2))) + display(frac(b c − a d, c^(2) + d^(2))) i$] ] + The product of a nonzero complex number and its conjugate is always a positive real number. #math.equation(block: true, alt: "z z bar equals open parenthesis a plus b i close parenthesis open parenthesis a minus b i close parenthesis equals a squared minus b squared i squared equals a squared minus b squared open parenthesis minus 1 close parenthesis equals a squared plus b squared")[$z overline(z) = ( a + b i ) ( a − b i ) = a^(2) − b^(2) i^(2) = a^(2) − b^(2) ( − 1 ) = a^(2) + b^(2)$]. + We can graph complex numbers in the complex plane. + We can visualize the sum of two complex numbers by vector addition in the complex plane. + #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[ #emph[Fundamental Theorem of Algebra] Let #math.equation(block: false, alt: "p open parenthesis x close parenthesis")[$p ( x )$] be a polynomial of degree #math.equation(block: false, alt: "n greater than or equal to 1")[$n ≥ 1$]. Then #math.equation(block: false, alt: "p open parenthesis x close parenthesis")[$p ( x )$] has exactly #math.equation(block: false, alt: "n")[$n$] complex zeros. ] + The nonreal zeros of a polynomial with real coefficients always occur in conjugate pairs. + Multiplying a complex number by #math.equation(block: false, alt: "i")[$i$] rotates its graph by #math.equation(block: false, alt: "90 degrees")[$90^(∘)$] around the origin. + #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[ #emph[Polar Form for a Complex Number] The complex number #math.equation(block: false, alt: "z equals a plus b i")[$z = a + b i$] can be written in the polar form #math.equation(block: true, alt: "z equals r open parenthesis cos ⁡ open parenthesis θ close parenthesis plus i sin ⁡ open parenthesis θ close parenthesis close parenthesis")[$z = r ( cos ( θ ) + i sin ( θ ) )$]where #math.equation(block: true, alt: "r equals the square root of a squared plus b squared")[$r = sqrt(a^(2) + b^(2))$]and #math.equation(block: false, alt: "θ")[$θ$] is defined by #math.equation(block: true, alt: "a equals r cos ⁡ open parenthesis θ close parenthesis , b equals r sin ⁡ open parenthesis θ close parenthesis , 0 less than or equal to θ less than or equal to 2 π")[$a = r cos ( θ ) , " " " " " " " " b = r sin ( θ ) , " " " " " " " " 0 ≤ θ ≤ 2 π$]The angle #math.equation(block: false, alt: "θ")[$θ$] is called the #strong[argument] of the complex number, and #math.equation(block: false, alt: "r")[$r$] is its length, or #strong[modulus]. ] + #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[ #emph[Product and Quotient in Polar Form] If #math.equation(block: false, alt: "z sub 1 equals r open parenthesis cos ⁡ α plus i sin ⁡ α close parenthesis")[$z_(1) = r ( cos α + i sin α )$] and #math.equation(block: false, alt: "z sub 2 equals R open parenthesis cos ⁡ β plus i sin ⁡ β close parenthesis")[$z_(2) = R ( cos β + i sin β )$], then #math.equation(block: true, alt: "z sub 1 z sub 2 equals r R open parenthesis cos ⁡ open parenthesis α plus β close parenthesis plus i sin ⁡ open parenthesis α plus β close parenthesis close parenthesis")[$z_(1) z_(2) = r R ( cos ( α + β ) + i sin ( α + β ) )$]and #math.equation(block: true, alt: "the fraction z sub 1 over z sub 2 equals the fraction r over R open parenthesis cos ⁡ open parenthesis α minus β close parenthesis plus i sin ⁡ open parenthesis α minus β close parenthesis close parenthesis")[$display(frac(z_(1), z_(2))) = display(frac(r, R)) ( cos ( α − β ) + i sin ( α − β ) )$] ] + #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[ #emph[De Moivre's Theorem] If #math.equation(block: false, alt: "z equals r open parenthesis cos ⁡ open parenthesis α close parenthesis plus i sin ⁡ open parenthesis α close parenthesis close parenthesis")[$z = r ( cos ( α ) + i sin ( α ) )$] is a complex number in polar form, and #math.equation(block: false, alt: "n")[$n$] is a positive integer, then #math.equation(block: true, alt: "z to the power n equals r to the power n open parenthesis cos ⁡ open parenthesis n α close parenthesis plus i sin ⁡ open parenthesis n α close parenthesis close parenthesis")[$z^(n) = r^(n) ( cos ( n α ) + i sin ( n α ) )$] ] + #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[ #emph[Roots of a Complex Number] A complex number #math.equation(block: false, alt: "z equals r open parenthesis cos ⁡ open parenthesis α close parenthesis plus i sin ⁡ open parenthesis α close parenthesis close parenthesis")[$z = r ( cos ( α ) + i sin ( α ) )$] in polar form has #math.equation(block: false, alt: "n")[$n$] complex #math.equation(block: false, alt: "n")[$n$]th roots, given by #math.equation(block: true, alt: "z sub k equals r to the power 1 / n open parenthesis cos ⁡ open parenthesis the fraction α plus 2 π k over n close parenthesis plus i sin ⁡ open parenthesis the fraction α plus 2 π k over n close parenthesis close parenthesis")[$bold(italic(z))_(bold(italic(k))) = bold(italic(r))^(1 / bold(italic(n))) ( bold(cos) ( display(frac(bold(italic(α)) + 2 bold(italic(π)) bold(italic(k)), bold(italic(n)))) ) + bold(italic(i)) bold(sin) ( display(frac(bold(italic(α)) + 2 bold(italic(π)) bold(italic(k)), bold(italic(n)))) ) )$]for #math.equation(block: false, alt: "k equals 0 , 1 , 2 , ⋯ , n minus 1")[$k = 0 , " " 1 , " " 2 , ⋯ , " " n − 1$]. ] === Review Problems For Problems 1–4, use the grid at right to plot the points whose polar coordinates are given. #figure(figph[polar grid], alt: "polar grid", caption: none) #math.equation(block: true, alt: "open parenthesis 4 , the fraction 5 π over 6 close parenthesis")[$( 4 , display(frac(5 π, 6)) )$] #figure(figph[polar plot], alt: "polar plot", caption: none) #math.equation(block: true, alt: "open parenthesis 1 , the fraction minus 5 π over 3 close parenthesis")[$( 1 , display(frac(− 5 π, 3)) )$] #math.equation(block: true, alt: "open parenthesis minus 3 , the fraction π over 2 close parenthesis")[$( − 3 , display(frac(π, 2)) )$] #figure(figph[polar plot], alt: "polar plot", caption: none) #math.equation(block: true, alt: "open parenthesis 2 , the fraction 7 π over 4 close parenthesis")[$( 2 , display(frac(7 π, 4)) )$] For Problems 5–8, convert the polar coordinates to Cartesian coordinates. #math.equation(block: true, alt: "open parenthesis 1 , the fraction 5 π over 4 close parenthesis")[$( 1 , display(frac(5 π, 4)) )$] #math.equation(block: true, alt: "open parenthesis the fraction minus the square root of 2 over 2 , the fraction minus the square root of 2 over 2 close parenthesis")[$( display(frac(− sqrt(2), 2)) , display(frac(− sqrt(2), 2)) )$] #math.equation(block: true, alt: "open parenthesis 0 , the fraction π over 12 close parenthesis")[$( 0 , display(frac(π, 12)) )$] #math.equation(block: true, alt: "open parenthesis 3.4 , minus 1.5 close parenthesis")[$( 3.4 , − 1.5 )$] #math.equation(block: true, alt: "open parenthesis 0.241 , minus 3.391 close parenthesis")[$( 0.241 , − 3.391 )$] #math.equation(block: true, alt: "open parenthesis minus 5.6 , minus 1.1 close parenthesis")[$( − 5.6 , − 1.1 )$] For Problems 9–12, convert the Cartesian coordinates to polar coordinates with #math.equation(block: false, alt: "r greater than or equal to 0")[$r ≥ 0$] and #math.equation(block: false, alt: "0 less than or equal to θ less than or equal to 2 π")[$0 ≤ θ ≤ 2 π$]. Give exact values for #math.equation(block: false, alt: "r")[$r$] and #math.equation(block: false, alt: "θ")[$θ$]. #math.equation(block: true, alt: "open parenthesis minus 3 , 3 close parenthesis")[$( − 3 , 3 )$] #math.equation(block: true, alt: "open parenthesis 3 the square root of 2 , the fraction 3 π over 4 close parenthesis")[$( 3 sqrt(2) , display(frac(3 π, 4)) )$] #math.equation(block: true, alt: "open parenthesis 0 , minus 2 close parenthesis")[$( 0 , − 2 )$] #math.equation(block: true, alt: "open parenthesis 5 , minus 2 close parenthesis")[$( 5 , − 2 )$] #math.equation(block: true, alt: "open parenthesis the square root of 29 , tan to the power minus 1 ⁡ open parenthesis the fraction minus 2 over 5 close parenthesis plus 2 π close parenthesis")[$( sqrt(29) , tan^(− 1) ( display(frac(− 2, 5)) ) + 2 π )$] #math.equation(block: true, alt: "open parenthesis minus 15 , minus 8 close parenthesis")[$( − 15 , − 8 )$] For Problems 13–16, sketch the region described by the inequalities. #math.equation(block: true, alt: "r greater than or equal to 0 , the fraction minus π over 4 less than or equal to θ less than or equal to the fraction π over 4")[$r ≥ 0 , " " display(frac(− π, 4)) ≤ θ ≤ display(frac(π, 4))$] #figure(figph[region on polar grid], alt: "region on polar grid", caption: none) #math.equation(block: true, alt: "1 less than or equal to r less than or equal to 3 , 0 less than or equal to θ less than or equal to π")[$1 ≤ r ≤ 3 , " " 0 ≤ θ ≤ π$] #math.equation(block: true, alt: "0 less than or equal to r less than or equal to 2")[$0 ≤ r ≤ 2$] #figure(figph[region on polar grid], alt: "region on polar grid", caption: none) #math.equation(block: true, alt: "r greater than or equal to 4")[$r ≥ 4$] For Problems 17–20, convert the equation into Cartesian coordinates. #math.equation(block: true, alt: "r equals 1")[$r = 1$] #math.equation(block: true, alt: "x squared plus y squared equals 1")[$x^(2) + y^(2) = 1$] #math.equation(block: true, alt: "r equals minus 3 sec ⁡ open parenthesis θ close parenthesis")[$r = − 3 sec ( θ )$] #math.equation(block: true, alt: "r equals the fraction 6 over 1 minus 2 cos ⁡ open parenthesis θ close parenthesis")[$r = display(frac(6, 1 − 2 cos ( θ )))$] #math.equation(block: true, alt: "x squared plus y squared equals open parenthesis 2 x plus 6 close parenthesis squared")[$x^(2) + y^(2) = ( 2 x + 6 )^(2)$] #math.equation(block: true, alt: "3 tan ⁡ open parenthesis θ close parenthesis equals 6 r sin ⁡ open parenthesis θ close parenthesis minus 1")[$3 tan ( θ ) = 6 r sin ( θ ) − 1$] For Problems 21–24, convert the equation into polar coordinates. #math.equation(block: true, alt: "x plus y equals 2")[$x + y = 2$] #math.equation(block: true, alt: "r cos ⁡ open parenthesis θ close parenthesis plus r sin ⁡ open parenthesis θ close parenthesis equals 2")[$r cos ( θ ) + r sin ( θ ) = 2$] #math.equation(block: true, alt: "the square root of x squared plus y squared equals 4 y")[$sqrt(x^(2) + y^(2)) = 4 y$] #math.equation(block: true, alt: "the fraction y over x equals the square root of x squared plus y squared")[$display(frac(y, x)) = sqrt(x^(2) + y^(2))$] #math.equation(block: true, alt: "tan ⁡ open parenthesis θ close parenthesis equals r")[$tan ( θ ) = r$] #math.equation(block: true, alt: "y squared equals 2 y equals x minus x squared")[$y^(2) = 2 y = x − x^(2)$] For Problems 25–28, use the catalog of polar graphs to help you identify and sketch the curve. Check your work by graphing with a calculator. #math.equation(block: true, alt: "r equals 3")[$r = 3$] Circle of radius 3 centered at the origin #math.equation(block: true, alt: "θ equals the fraction 3 π over 4")[$θ = display(frac(3 π, 4))$] #math.equation(block: true, alt: "r equals 6 cos ⁡ open parenthesis θ close parenthesis")[$r = 6 cos ( θ )$] Circle of radius 3 centered at #math.equation(block: false, alt: "open parenthesis 3 , 0 close parenthesis")[$( 3 , 0 )$] #math.equation(block: true, alt: "r squared equals 9 sin ⁡ open parenthesis 2 θ close parenthesis")[$r^(2) = 9 sin ( 2 θ )$] For Problems 29–32, write a polar equation for the graph. #figure(figph[polar grid], alt: "polar grid", caption: none) #math.equation(block: true, alt: "r equals 4")[$r = 4$] #figure(figph[polar grid], alt: "polar grid", caption: none) #figure(figph[polar grid], alt: "polar grid", caption: none) #math.equation(block: true, alt: "r equals 4 cos ⁡ open parenthesis θ close parenthesis")[$r = 4 cos ( θ )$] #figure(figph[polar grid], alt: "polar grid", caption: none) For Problems 33–36, find the coordinates of the intersection points of the two curves analytically. Then graph the curves to verify your answers. #math.equation(block: true, alt: "r equals 3 plus 2 sin ⁡ open parenthesis θ close parenthesis , r equals 4")[$r = 3 + 2 sin ( θ ) , " " r = 4$] #math.equation(block: true, alt: "open parenthesis 4 , the fraction π over 6 close parenthesis")[$( 4 , display(frac(π, 6)) )$], #math.equation(block: true, alt: "open parenthesis 4 , the fraction 5 π over 6 close parenthesis")[$" " ( 4 , display(frac(5 π, 6)) )$] #math.equation(block: true, alt: "r equals 3 cos ⁡ open parenthesis θ close parenthesis , r equals the square root of 3 sin ⁡ open parenthesis θ close parenthesis")[$r = 3 cos ( θ ) , " " r = sqrt(3) sin ( θ )$] #math.equation(block: true, alt: "r equals 4 sin ⁡ open parenthesis θ close parenthesis , r equals minus 4 cos ⁡ open parenthesis θ close parenthesis")[$r = 4 sin ( θ ) , " " r = − 4 cos ( θ )$] #math.equation(block: false, alt: "open parenthesis 2 the square root of 2 , the fraction 3 π over 4 close parenthesis")[$( 2 sqrt(2) , display(frac(3 π, 4)) )$] and the pole #math.equation(block: true, alt: "r equals 2 plus 6 sin ⁡ open parenthesis θ close parenthesis , r equals 4 sin ⁡ open parenthesis θ close parenthesis")[$r = 2 + 6 sin ( θ ) , " " r = 4 sin ( θ )$] For Problems 37–40, perform the indicated operations on the complex numbers. #math.equation(block: true, alt: "the fraction 5 minus 10 i over 2 minus i")[$display(frac(5 − 10 i, 2 − i))$] #math.equation(block: true, alt: "4 minus 3 i")[$4 − 3 i$] #math.equation(block: true, alt: "open parenthesis 4 minus 7 i close parenthesis open parenthesis 1 plus i close parenthesis")[$( 4 − 7 i ) ( 1 + i )$] #math.equation(block: true, alt: "5 i open parenthesis 2 minus i close parenthesis minus open parenthesis 7 plus 6 i close parenthesis")[$5 i ( 2 − i ) − ( 7 + 6 i )$] #math.equation(block: true, alt: "minus 2 plus 4 i")[$− 2 + 4 i$] #math.equation(block: true, alt: "minus 8 plus 3 i plus the fraction 9 minus 4 i over i")[$− 8 + 3 i + display(frac(9 − 4 i, i))$] For Problems 41–44, evaluate the polynomial for the given values of the variable. #math.equation(block: true, alt: "z squared plus 4 z plus 6")[$z^(2) + 4 z + 6$] + #math.equation(block: false, alt: "z equals minus 2 plus i")[$z = − 2 + i$] + #math.equation(block: false, alt: "z equals minus 2 minus 1")[$z = − 2 − 1$] + #math.equation(block: false, alt: "1")[$1$] + #math.equation(block: false, alt: "1")[$1$] #math.equation(block: true, alt: "z squared minus 6 z plus 12")[$z^(2) − 6 z + 12$] + #math.equation(block: false, alt: "z equals 3 minus 2 i")[$z = 3 − 2 i$] + #math.equation(block: false, alt: "z equals 3 plus 21")[$z = 3 + 21$] #math.equation(block: true, alt: "3 w squared minus 18 w plus 31")[$3 w^(2) − 18 w + 31$] + #math.equation(block: false, alt: "w equals 3 plus 4 i")[$w = 3 + 4 i$] + #math.equation(block: false, alt: "w equals 3 minus 4 i")[$w = 3 − 4 i$] + #math.equation(block: false, alt: "minus 44")[$− 44$] + #math.equation(block: false, alt: "minus 44")[$− 44$] #math.equation(block: true, alt: "2 w squared plus 8 w plus 11")[$2 w^(2) + 8 w + 11$] + #math.equation(block: false, alt: "w equals minus 2 minus 5 i")[$w = − 2 − 5 i$] + #math.equation(block: false, alt: "w equals minus 2 plus 51")[$w = − 2 + 51$] Verify that #math.equation(block: false, alt: "z sub 1 equals 2 plus i")[$z_(1) = 2 + i$] and #math.equation(block: false, alt: "z sub 2 equals 2 minus i")[$z_(2) = 2 − i$] are roots of the equation #math.equation(block: false, alt: "x squared minus 4 x plus 5 equals 0")[$x^(2) − 4 x + 5 = 0$]. #math.equation(block: true, alt: "open parenthesis 2 plus or minus i close parenthesis squared minus 4 open parenthesis 2 plus or minus i close parenthesis plus 5 equals open parenthesis 4 plus or minus 4 i minus 1 close parenthesis minus open parenthesis 8 plus or minus 4 i close parenthesis plus 5 equals 0")[$( 2 ± i )^(2) − 4 ( 2 ± i ) + 5 = ( 4 ± 4 i − 1 ) − ( 8 ± 4 i ) + 5 = 0$] Verify that #math.equation(block: false, alt: "z sub 1 equals minus 3 plus 4 i")[$z_(1) = − 3 + 4 i$] and #math.equation(block: false, alt: "z sub 2 equals minus 3 minus 4 i")[$z_(2) = − 3 − 4 i$] are roots of the equation #math.equation(block: false, alt: "x squared plus 6 x plus 25 equals 0")[$x^(2) + 6 x + 25 = 0$]. For Problems 47–50, expand the product of polynomials. #math.equation(block: true, alt: "open bracket z minus open parenthesis minus 2 plus i close parenthesis close bracket open bracket z minus open parenthesis minus 2 minus i close parenthesis close bracket")[$[ z − ( − 2 + i ) ] [ z − ( − 2 − i ) ]$] #math.equation(block: true, alt: "z squared plus 4 z plus 5")[$z^(2) + 4 z + 5$] #math.equation(block: true, alt: "open bracket w minus open parenthesis 1 plus 3 i close parenthesis close bracket open bracket w minus open parenthesis 1 minus 3 i close parenthesis close bracket close parenthesis close bracket")[$\[ w − \( 1 + 3 i \) \] \[ w − \( 1 − 3 i \) \] \) \]$] #math.equation(block: true, alt: "open bracket s plus open parenthesis 5 plus 4 i close parenthesis close bracket open bracket s plus open parenthesis 5 minus 4 i close parenthesis close bracket")[$[ s + ( 5 + 4 i ) ] [ s + ( 5 − 4 i ) ]$] #math.equation(block: true, alt: "s squared minus 10 s plus 41")[$s^(2) − 10 s + 41$] #math.equation(block: true, alt: "open bracket x plus open parenthesis minus 6 plus i close parenthesis close bracket open bracket x plus open parenthesis minus 6 minus i close parenthesis close bracket")[$[ x + ( − 6 + i ) ] [ x + ( − 6 − i ) ]$] For Problems 51–52, sketch the set of points in the complex plane. #math.equation(block: true, alt: "z sub 1 equals minus 3 plus 2 i ,")[$z_(1) = − 3 + 2 i , " "$] #math.equation(block: true, alt: "z sub 2 equals minus 3 minus 2 i ,")[$z_(2) = − 3 − 2 i , " "$] #math.equation(block: true, alt: "z sub 3 equals 3 plus 2 i ,")[$z_(3) = 3 + 2 i , " "$] #math.equation(block: true, alt: "z sub 4 equals 3 minus 2 i")[$z_(4) = 3 − 2 i$] #figure(figph[complex numbers], alt: "complex numbers", caption: none) #math.equation(block: true, alt: "w sub 1 equals 4 minus 6 i ,")[$w_(1) = 4 − 6 i , " "$] #math.equation(block: true, alt: "w sub 2 equals 4 plus 6 i ,")[$w_(2) = 4 + 6 i , " "$] #math.equation(block: true, alt: "w sub 3 equals minus 4 minus 6 i ,")[$w_(3) = − 4 − 6 i , " "$] #math.equation(block: true, alt: "w sub 4 equals minus 4 plus 6 i")[$w_(4) = − 4 + 6 i$] For Problems 53–56, + Given one solution of a quadratic equation with rational coefficients, find the other solution. + Write a quadratic equation that has those solutions. #math.equation(block: true, alt: "minus 1 plus 7 i")[$− 1 + 7 i$] + #math.equation(block: false, alt: "minus 1 minus 7 i")[$− 1 − 7 i$] + #math.equation(block: false, alt: "x squared plus 2 x plus 50 equals 0")[$x^(2) + 2 x + 50 = 0$] #math.equation(block: true, alt: "2 minus 5 i")[$2 − 5 i$] #math.equation(block: true, alt: "3 minus the square root of 2 i")[$3 − sqrt(2) i$] + #math.equation(block: false, alt: "3 plus the square root of 2 i")[$3 + sqrt(2) i$] + #math.equation(block: false, alt: "x squared minus 6 x plus 11 equals 0")[$x^(2) − 6 x + 11 = 0$] #math.equation(block: true, alt: "4 plus the square root of 3 i")[$4 + sqrt(3) i$] For Problems 57–60, write the complex numbers in standard form. Give exact values for your answers. #math.equation(block: true, alt: "10 open parenthesis cos ⁡ open parenthesis the fraction minus π over 6 close parenthesis plus i sin ⁡ open parenthesis the fraction minus π over 6 close parenthesis close parenthesis")[$10 ( cos ( display(frac(− π, 6)) ) + i sin ( display(frac(− π, 6)) ) )$] #math.equation(block: true, alt: "5 the square root of 3 minus 5 i")[$5 sqrt(3) − 5 i$] #math.equation(block: true, alt: "8 open parenthesis cos ⁡ open parenthesis the fraction 5 π over 4 close parenthesis plus i sin ⁡ open parenthesis the fraction 5 π over 4 close parenthesis close parenthesis")[$8 ( cos ( display(frac(5 π, 4)) ) + i sin ( display(frac(5 π, 4)) ) )$] #math.equation(block: true, alt: "5 the square root of 2 open parenthesis cos ⁡ open parenthesis the fraction π over 4 close parenthesis plus i sin ⁡ open parenthesis the fraction π over 4 close parenthesis close parenthesis")[$5 sqrt(2) ( cos ( display(frac(π, 4)) ) + i sin ( display(frac(π, 4)) ) )$] #math.equation(block: true, alt: "5 plus 5 i")[$5 + 5 i$] #math.equation(block: true, alt: "6 the square root of 3 open parenthesis cos ⁡ open parenthesis the fraction minus π over 3 close parenthesis plus i sin ⁡ open parenthesis the fraction minus π over 3 close parenthesis close parenthesis")[$6 sqrt(3) ( cos ( display(frac(− π, 3)) ) + i sin ( display(frac(− π, 3)) ) )$] For Problems 61–66, write the complex numbers in polar form. Give exact values for your answers. #math.equation(block: true, alt: "3 minus 3 i")[$3 − 3 i$] #math.equation(block: true, alt: "3 the square root of 2 open parenthesis cos ⁡ open parenthesis the fraction 7 π over 4 close parenthesis plus i sin ⁡ open parenthesis the fraction 7 π over 4 close parenthesis close parenthesis")[$3 sqrt(2) ( cos ( display(frac(7 π, 4)) ) + i sin ( display(frac(7 π, 4)) ) )$] #math.equation(block: true, alt: "minus 4 minus 4 i")[$− 4 − 4 i$] #math.equation(block: true, alt: "minus 5")[$− 5$] #math.equation(block: true, alt: "5 open parenthesis cos ⁡ open parenthesis π close parenthesis plus i sin ⁡ open parenthesis π close parenthesis close parenthesis")[$5 ( cos ( π ) + i sin ( π ) )$] #math.equation(block: true, alt: "minus 7 i")[$− 7 i$] #math.equation(block: true, alt: "minus 1 minus the square root of 3 i")[$− 1 − sqrt(3) i$] #math.equation(block: true, alt: "2 open parenthesis cos ⁡ open parenthesis the fraction 4 π over 3 close parenthesis plus i sin ⁡ open parenthesis the fraction 4 π over 3 close parenthesis close parenthesis")[$2 ( cos ( display(frac(4 π, 3)) ) + i sin ( display(frac(4 π, 3)) ) )$] #math.equation(block: true, alt: "6 plus 2 the square root of 3 i")[$6 + 2 sqrt(3) i$] For Problems 67–70, find the product #math.equation(block: false, alt: "z sub 1 z sub 2")[$z_(1) z_(2)$] and the quotient #math.equation(block: false, alt: "the fraction z sub 1 over z sub 2")[$display(frac(z_(1), z_(2)))$]. #math.equation(block: true, alt: "z sub 1 equals 8 open parenthesis cos ⁡ open parenthesis the fraction π over 6 close parenthesis plus i sin ⁡ open parenthesis the fraction π over 6 close parenthesis close parenthesis")[$z_(1) = 8 ( cos ( display(frac(π, 6)) ) + i sin ( display(frac(π, 6)) ) )$] #math.equation(block: true, alt: "z sub 2 equals 2 open parenthesis cos ⁡ open parenthesis the fraction 5 π over 6 close parenthesis plus i sin ⁡ open parenthesis the fraction 5 π over 6 close parenthesis close parenthesis")[$z_(2) = 2 ( cos ( display(frac(5 π, 6)) ) + i sin ( display(frac(5 π, 6)) ) )$] #math.equation(block: true, alt: "z sub 1 z sub 2, equals 16 open parenthesis cos ⁡ open parenthesis π close parenthesis plus i sin ⁡ open parenthesis π close parenthesis close parenthesis; equals minus 16 , the fraction z sub 1 over z sub 2; equals 4 open parenthesis cos ⁡ open parenthesis the fraction minus 2 π over 3 close parenthesis plus i sin ⁡ open parenthesis the fraction minus 2 π over 3 close parenthesis close parenthesis; equals minus 2 minus 2 the square root of 3 i")[$z_(1) z_(2) & = 16 ( cos ( π ) + i sin ( π ) ) \ & = − 16 , " " display(frac(z_(1), z_(2))) \ & = 4 ( cos ( display(frac(− 2 π, 3)) ) + i sin ( display(frac(− 2 π, 3)) ) ) \ & = − 2 − 2 sqrt(3) i$] #math.equation(block: true, alt: "z sub 1 equals 9 open parenthesis cos ⁡ open parenthesis the fraction minus 2 π over 3 close parenthesis plus i sin ⁡ open parenthesis the fraction minus 2 π over 3 close parenthesis close parenthesis")[$z_(1) = 9 ( cos ( display(frac(− 2 π, 3)) ) + i sin ( display(frac(− 2 π, 3)) ) )$]#math.equation(block: true, alt: "z sub 2 equals 3 open parenthesis cos ⁡ open parenthesis the fraction π over 3 close parenthesis plus i sin ⁡ open parenthesis the fraction π over 3 close parenthesis close parenthesis")[$z_(2) = 3 ( cos ( display(frac(π, 3)) ) + i sin ( display(frac(π, 3)) ) )$] #math.equation(block: true, alt: "z sub 1 equals 5 open parenthesis cos ⁡ open parenthesis the fraction minus 7 π over 12 close parenthesis plus i sin ⁡ open parenthesis the fraction minus 7 π over 12 close parenthesis close parenthesis")[$z_(1) = 5 ( cos ( display(frac(− 7 π, 12)) ) + i sin ( display(frac(− 7 π, 12)) ) )$]#math.equation(block: true, alt: "z sub 2 equals the fraction 1 over 2 open parenthesis cos ⁡ open parenthesis open parenthesis the fraction π over 4 close parenthesis plus i sin ⁡ open parenthesis the fraction π over 4 close parenthesis close parenthesis close parenthesis")[$z_(2) = display(frac(1, 2)) ( cos ( ( display(frac(π, 4)) ) + i sin ( display(frac(π, 4)) ) ) )$] #math.equation(block: true, alt: "z sub 1 z sub 2, equals the fraction 5 over 2 open parenthesis cos ⁡ open parenthesis the fraction minus π over 3 close parenthesis plus i sin ⁡ open parenthesis the fraction minus π over 3 close parenthesis close parenthesis; equals the fraction 5 over 4 minus the fraction 5 the square root of 3 over 2 i ,")[$z_(1) z_(2) & = display(frac(5, 2)) ( cos ( display(frac(− π, 3)) ) + i sin ( display(frac(− π, 3)) ) ) \ & = display(frac(5, 4)) − display(frac(5 sqrt(3), 2)) i ,$] #math.equation(block: true, alt: "the fraction z sub 1 over z sub 2, equals 10 open parenthesis cos ⁡ open parenthesis the fraction minus 5 π over 6 close parenthesis plus i sin ⁡ open parenthesis the fraction minus 5 π over 6 close parenthesis close parenthesis; equals minus 5 the square root of 3 minus 5 i")[$display(frac(z_(1), z_(2))) & = 10 ( cos ( display(frac(− 5 π, 6)) ) + i sin ( display(frac(− 5 π, 6)) ) ) \ & = − 5 sqrt(3) − 5 i$] #math.equation(block: true, alt: "z sub 1 equals 14 open parenthesis cos ⁡ open parenthesis the fraction 3 π over 2 close parenthesis plus i sin ⁡ open parenthesis the fraction 3 π over 2 close parenthesis close parenthesis")[$z_(1) = 14 ( cos ( display(frac(3 π, 2)) ) + i sin ( display(frac(3 π, 2)) ) )$]#math.equation(block: true, alt: "z sub 2 equals 2 open parenthesis cos ⁡ the fraction π over 6 plus i sin ⁡ the fraction π over 6 close parenthesis")[$z_(2) = 2 ( cos display(frac(π, 6)) + i sin display(frac(π, 6)) )$] For Problems 71–74, find the power. #math.equation(block: true, alt: "open parenthesis the fraction the square root of 3 over 2 plus the fraction 1 over 2 i close parenthesis to the power 12")[$attach(( display(frac(sqrt(3), 2)) + display(frac(1, 2)) i ), t: 12)$] #math.equation(block: true, alt: "1")[$1$] #math.equation(block: true, alt: "open parenthesis 1 minus the square root of 3 i close parenthesis to the power 6")[$attach(( 1 − sqrt(3) i ), t: 6)$] #math.equation(block: true, alt: "open parenthesis minus the square root of 5 plus the square root of 5 i close parenthesis to the power minus 4")[$attach(( − sqrt(5) + sqrt(5) i ), t: − 4)$] #math.equation(block: true, alt: "the fraction minus 1 over 100")[$display(frac(− 1, 100))$] #math.equation(block: true, alt: "open parenthesis minus 1 minus i close parenthesis to the power minus 8")[$( − 1 − i )^(− 8)$] For Problems 75–78, + Find the roots and plot them in the complex plane. + Write the roots in standard form. The square roots of #math.equation(block: false, alt: "minus 16 i")[$− 16 i$] + #figure(figph[complex square roots], alt: "complex square roots", caption: none) + #math.equation(block: false, alt: "minus 2 the square root of 2 plus 2 the square root of 2 i")[$− 2 sqrt(2) + 2 sqrt(2) i$], #math.equation(block: false, alt: "2 the square root of 2 minus 2 the square root of 2 i")[$" " 2 sqrt(2) − 2 sqrt(2) i$] The cube roots of #math.equation(block: false, alt: "minus 8")[$− 8$] The cube roots of #math.equation(block: false, alt: "minus 27 i")[$− 27 i$] + #figure(figph[complex cube roots], alt: "complex cube roots", caption: none) + #math.equation(block: false, alt: "3 i")[$3 i$], #math.equation(block: false, alt: "the fraction minus 3 the square root of 3 over 2 minus the fraction 3 over 2 i")[$" " display(frac(− 3 sqrt(3), 2)) − display(frac(3, 2)) i$], #math.equation(block: false, alt: "the fraction 3 the square root of 3 over 2 minus the fraction 3 over 2 i")[$" " display(frac(3 sqrt(3), 2)) − display(frac(3, 2)) i$] The square roots of #math.equation(block: false, alt: "minus 2 plus 2 the square root of 3 i")[$− 2 + 2 sqrt(3) i$] For Problems 79–82, solve the equation. #math.equation(block: true, alt: "z to the power 6 plus 27 equals 0")[$z^(6) + 27 = 0$] #math.equation(block: false, alt: "3 open parenthesis cos ⁡ θ plus i sin ⁡ θ close parenthesis ,")[$3 ( cos θ + i sin θ ) ,$] for #math.equation(block: false, alt: "θ equals the fraction π over 6 ,")[$θ = display(frac(π, 6)) , " "$] #math.equation(block: false, alt: "the fraction π over 2 ,")[$display(frac(π, 2)) , " "$] #math.equation(block: false, alt: "the fraction 5 π over 6 ,")[$display(frac(5 π, 6)) , " "$] #math.equation(block: false, alt: "the fraction 7 π over 6 ,")[$display(frac(7 π, 6)) , " "$] #math.equation(block: false, alt: "the fraction 3 π over 2 ,")[$display(frac(3 π, 2)) , " "$] #math.equation(block: false, alt: "the fraction 11 π over 6")[$display(frac(11 π, 6))$] #math.equation(block: true, alt: "z to the power 4 minus 6 z squared plus 12 equals 0")[$z^(4) − 6 z^(2) + 12 = 0$] #math.equation(block: true, alt: "z to the power 4 plus 2 z squared plus 4 equals 0")[$z^(4) + 2 z^(2) + 4 = 0$] #math.equation(block: false, alt: "the square root of 2 open parenthesis cos ⁡ open parenthesis θ close parenthesis plus i sin ⁡ open parenthesis θ close parenthesis close parenthesis ,")[$sqrt(2) ( cos ( θ ) + i sin ( θ ) ) ,$] for #math.equation(block: false, alt: "θ equals the fraction π over 3 ,")[$θ = display(frac(π, 3)) , " "$] #math.equation(block: false, alt: "the fraction 2 π over 3 ,")[$display(frac(2 π, 3)) , " "$] #math.equation(block: false, alt: "the fraction 4 π over 3 ,")[$display(frac(4 π, 3)) , " "$] #math.equation(block: false, alt: "the fraction 5 π over 3")[$display(frac(5 π, 3))$] #math.equation(block: true, alt: "z to the power 6 minus 8 equals 0")[$z^(6) − 8 = 0$]