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: 57

Answer

$ 2(cos67.5^\circ+i\ sin67.5^\circ)$, $ 2(cos157.5^\circ+i\ sin157.5^\circ)$, $ 2(cos247.5^\circ+i\ sin247.5^\circ)$, $ 2(cos337.5^\circ+i\ sin337.5^\circ)$.

Work Step by Step

Based on the given conditions, we have: $-16i=16(cos270^\circ+i\ sin270^\circ)$, $(-16i)^{1/4}=2(cos(\frac{360k+270}{4})^\circ+i\ sin(\frac{360k+270}{4})^\circ)$, $k=0, z_0= 2(cos67.5^\circ+i\ sin67.5^\circ)$, $k=1, z_1= 2(cos157.5^\circ+i\ sin157.5^\circ)$, $k=2, z_2= 2(cos247.5^\circ+i\ sin247.5^\circ)$, $k=3, z_3= 2(cos337.5^\circ+i\ sin337.5^\circ)$.
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