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: 84

Answer

$w_0=cos~\frac{\pi}{10}+i~sin~\frac{\pi}{10}$ $w_1=i$ $w_2=cos~\frac{9\pi}{10}+i~sin~\frac{9\pi}{10}$ $w_3=cos~\frac{13\pi}{10}+i~sin~\frac{13\pi}{10}$ $w_4=cos~\frac{17\pi}{10}+i~sin~\frac{17\pi}{10}$

Work Step by Step

$r=|z|=1$ $θ=\frac{\pi}{2}~~$ (Positive imaginary axis) Polar form: $z=1(cos~\frac{\pi}{2}+i~sin~\frac{\pi}{2})$ $w_k=\sqrt[5] 1[cos(\frac{\frac{\pi}{2}+2k\pi}{5})+i~sin(\frac{\frac{\pi}{2}+2k\pi}{5})]$ $w_0=1(cos~\frac{\pi}{10}+i~sin~\frac{\pi}{10})$ $w_1=1(cos~\frac{\pi}{2}+i~sin~\frac{\pi}{2})=i$ $w_2=1(cos~\frac{9\pi}{10}+i~sin~\frac{9\pi}{10})$ $w_3=1(cos~\frac{13\pi}{10}+i~sin~\frac{13\pi}{10})$ $w_4=1(cos~\frac{17\pi}{10}+i~sin~\frac{17\pi}{10})$
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