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: 40

Answer

$zw=2\sqrt 2(cos255^\circ+i\ sin255^\circ), \frac{z}{w}=\frac{\sqrt 2}{2}(cos15^\circ+i\ sin15^\circ)$

Work Step by Step

Given $z=1-i=\sqrt 2(cos315^\circ+i\ sin315^\circ)$ and $w=1-\sqrt 3i= 2(cos300^\circ+i\ sin300^\circ)$ 1. $zw=2\sqrt 2(cos(315+300)^\circ+i\ sin(315+300)^\circ)=2\sqrt 2(cos255^\circ+i\ sin255^\circ)$ 2. $\frac{z}{w}=\frac{\sqrt 2}{2}(cos(315-300)^\circ+i\ sin(315-300)^\circ)=\frac{\sqrt 2}{2}(cos15^\circ+i\ sin15^\circ)$
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