Precalculus (6th Edition)

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

Chapter 7 - Trigonometric Identities and Equations - 7.4 Double-Angle and Half-Angle Identities - 7.4 Exercises: 8

Answer

Positive sign

Work Step by Step

$\theta =58^{0}\left( Q1;0\leq \theta \leq 90\right) $ Angle is located in quadrant 1 so we should choose positive sign (Cosine is positive in quadrant 1)
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