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: 53

Answer

$ \sqrt[6] 2(cos15^\circ+i\ sin15^\circ)$, $ \sqrt[6] 2(cos135^\circ+i\ sin135^\circ)$, $ \sqrt[6] 2(cos255^\circ+i\ sin255^\circ)$.

Work Step by Step

Based on the given conditions, we have: $1+i=\sqrt 2(cos45^\circ+i\ sin45^\circ)$, $(1+i)^{1/3}=\sqrt[6] 2(cos(\frac{360k+45}{3})^\circ+i\ sin(\frac{360k+45}{3})^\circ)$, $k=0, z_0=\sqrt[6] 2(cos15^\circ+i\ sin15^\circ)$, $k=1, z_1=\sqrt[6] 2(cos135^\circ+i\ sin135^\circ)$, $k=2, z_2=\sqrt[6] 2(cos255^\circ+i\ sin255^\circ)$.
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