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: 3

Answer

$3\rightarrow B$

Work Step by Step

$2\sin \alpha \cos \alpha =\sin 2\alpha \Rightarrow 2\sin 22.5\cos 22.5=\sin \left( 2\times 22.5\right) =\sin 45=\dfrac {\sqrt {2}}{2}$ $3\rightarrow B$
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