Trigonometry (11th Edition) Clone

Published by Pearson
ISBN 10: 978-0-13-421743-7
ISBN 13: 978-0-13421-743-7

Chapter 5 - Trigonometric Identities - Section 5.3 Sum and Difference Identities for Cosine - 5.3 Exercises - Page 219: 43



Work Step by Step

$$A=\cos(0^\circ-\theta)$$ Apply the cosine difference identity, which states $$\cos(A-B)=\cos A\cos B+\sin A\sin B$$ we have $$A=\cos0^\circ\cos\theta+\sin0^\theta\sin\theta$$ $$A=1\times\cos\theta+0\times\sin\theta$$ $$A=\cos\theta$$
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