Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 8 - Review - Exercises - Page 623: 42

Answer

$w_0=cos~\frac{\pi}{16}+i~sin~\frac{\pi}{16}$ $w_1=cos~\frac{5\pi}{16}+i~sin~\frac{5\pi}{16}$ $w_2=cos~\frac{9\pi}{16}+i~sin~\frac{9\pi}{16}$ $w_3=cos~\frac{13\pi}{16}+i~sin~\frac{13\pi}{16}$ $w_4=cos~\frac{17\pi}{16}+i~sin~\frac{17\pi}{16}$ $w_5=cos~\frac{21\pi}{16}+i~sin~\frac{21\pi}{16}$ $w_6=cos~\frac{25\pi}{16}+i~sin~\frac{25\pi}{16}$ $w_7=cos~\frac{29\pi}{16}+i~sin~\frac{29\pi}{16}$

Work Step by Step

$r=|z|=1$ $θ=\frac{\pi}{2}~~$ (Positive imaginary axis) Polar form: $z=1=1(cos~\frac{\pi}{2}+i~sin~\frac{\pi}{2})$ $w_k=\sqrt[8] {1}[cos(\frac{\frac{\pi}{2}+2k\pi}{8})+i~sin(\frac{\frac{\pi}{2}+2k\pi}{8})]$ $w_0=1(cos~\frac{\pi}{16}+i~sin~\frac{\pi}{16})$ $w_1=1(cos~\frac{5\pi}{16}+i~sin~\frac{5\pi}{16})$ $w_2=1(cos~\frac{9\pi}{16}+i~sin~\frac{9\pi}{16})$ $w_3=1(cos~\frac{13\pi}{16}+i~sin~\frac{13\pi}{16})$ $w_4=1(cos~\frac{17\pi}{16}+i~sin~\frac{17\pi}{16})$ $w_5=1(cos~\frac{21\pi}{16}+i~sin~\frac{21\pi}{16})$ $w_6=1(cos~\frac{25\pi}{16}+i~sin~\frac{25\pi}{16})$ $w_7=1(cos~\frac{29\pi}{16}+i~sin~\frac{29\pi}{16})$
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