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 - Section 8.3 The Complex Plane; De Moivre's Theorem - 8.3 Assess Your Understanding - Page 615: 56

Answer

$ 2\sqrt[6] 2(cos75^\circ+i\ sin75^\circ)$, $ 2\sqrt[6] 2(cos195^\circ+i\ sin195^\circ)$, $ 2\sqrt[6] 2(cos315^\circ+i\ sin315^\circ)$.

Work Step by Step

Based on the given conditions, we have: $-8-8i=8\sqrt 2(cos225^\circ+i\ sin225^\circ)$, $(-8-8i)^{1/3}=2\sqrt[6] 2(cos(\frac{360k+225}{3})^\circ+i\ sin(\frac{360k+225}{3})^\circ)$, $k=0, z_0=2\sqrt[6] 2(cos75^\circ+i\ sin75^\circ)$, $k=1, z_1=2\sqrt[6] 2(cos195^\circ+i\ sin195^\circ)$, $k=2, z_2=2\sqrt[6] 2(cos315^\circ+i\ sin315^\circ)$.
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