Precalculus (6th Edition)

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

Chapter 7 - Trigonometric Identities and Equations - 7.3 Sum and Difference Identities - 7.3 Exercises - Page 678: 5



Work Step by Step

$\cos \left( x-\dfrac {\pi }{2}\right) =\cos x\cos \dfrac {\pi }{2}+\sin x\sin \dfrac {\pi }{2}=\cos x\times 0+\sin x\times 1=\sin x\Rightarrow 5\rightarrow D$
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