Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 8 - Section 8.3 - Polar Form of Complex Numbers; De Moivre's Theorem - 8.3 Exercises - Page 611: 83

Answer

$w_0=\frac{\sqrt 3}{2}+\frac{1}{2}i$ $w_1=-\frac{\sqrt 3}{2}+\frac{1}{2}i$ $w_2=-i$

Work Step by Step

$r=|z|=1$ $θ=\frac{\pi}{2}~~$ (Positive imaginary axis) Polar form: $z=1(cos~\frac{\pi}{2}+i~sin~\frac{\pi}{2})$ $w_k=\sqrt[3] 1[cos(\frac{\frac{\pi}{2}+2k\pi}{3})+i~sin(\frac{\frac{\pi}{2}+2k\pi}{3})]$ $w_0=1(cos~\frac{\pi}{6}+i~sin~\frac{\pi}{6})=\frac{\sqrt 3}{2}+\frac{1}{2}i$ $w_1=1(cos~\frac{5\pi}{6}+i~sin~\frac{5\pi}{6})=-\frac{\sqrt 3}{2}+\frac{1}{2}i$ $w_2=1(cos~\frac{3\pi}{2}+i~sin~\frac{3\pi}{2})=-i$
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