Answer
E
Work Step by Step
$\sin \left( \dfrac {\pi }{2}-x\right) =\sin \dfrac {\pi }{2}\cos x-\cos \dfrac {\pi }{2}\sin x=1\times \cos x-0\times \sin x=\cos x\Rightarrow 4\rightarrow E$
Precalculus (6th Edition)
by Lial, Margaret L.; Hornsby, John; Schneider, David I.; Daniels, Callie
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: 4
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