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: 35

Answer

$zw=12(cos40^\circ+i\ sin40^\circ), \frac{z}{w}=\frac{3}{4}(cos220^\circ+i\ sin220^\circ)$

Work Step by Step

Given $z=3(cos130^\circ+i\ sin130^\circ)$ and $w=4(cos270^\circ+i\ sin270^\circ)$, we have: 1. $zw=12(cos(130+270)^\circ+i\ sin(130+270)^\circ)=12(cos(360+40)^\circ+i\ sin(360+40)^\circ)=12(cos40^\circ+i\ sin40^\circ)$ 2. $\frac{z}{w}=\frac{3}{4}(cos(130-270)^\circ+i\ sin(130-270)^\circ)=\frac{3}{4}(cos(-140)^\circ+i\ sin(-140)^\circ)=\frac{3}{4}(cos220^\circ+i\ sin220^\circ)$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.