Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 7 - Trigonometric Identities and Equations - 7.6 Trigonometric Equations - 7.6 Exercises - Page 720: 23



Work Step by Step

$\cos^2 x+2\cos x+1=0$ $(\cos x+1)^2=0$ $\cos x+1=0$ $\cos x=-1$ The only solution in $[0, 2\pi)$ is $\pi$.
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