Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 8 - Polar Coordinates; Vectors - Chapter Review - Review Exercises - Page 655: 26

Answer

$3, -\frac{3}{2}+\frac{3\sqrt 3}{2}i,-\frac{3}{2}-\frac{3\sqrt 3}{2}i$

Work Step by Step

1. Use the given conditions, we have: $z=27=27+0i=27(1+0i)=27(cos0+i\ sin0)$ 2. Thus $z^{1/3}=[27(cos0+i\ sin0)]^{1/3}=3(cos\frac{2k\pi}{3}+i\ sin\frac{2k\pi}{3})$ 3. For $k=0, z_0=3(cos0+i\ sin0)=3$ 4. For $k=1, z_1=3(cos\frac{2\pi}{3}+i\ sin\frac{2\pi}{3})=3(-\frac{1}{2}+\frac{\sqrt 3}{2}i)=-\frac{3}{2}+\frac{3\sqrt 3}{2}i$ 5. For $k=2, z_2=3(cos\frac{4\pi}{3}+i\ sin\frac{4\pi}{3})=3(-\frac{1}{2}-\frac{\sqrt 3}{2}i)=-\frac{3}{2}-\frac{3\sqrt 3}{2}i$
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