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 5.1 Fundamental Identities - 5.1 Exercises - Page 201: 43


$$\cos^2 x=\frac{1}{\sec^2 x}$$ $\text{B}$ is the answer.

Work Step by Step

$$A=\cos^2 x$$ According to this Reciprocal Identity: $$\sec\theta=\frac{1}{\cos\theta}$$ $$\cos\theta=\frac{1}{\sec\theta}$$ Therefore, $A$ can be rewritten as follows: $$A=\frac{1}{\sec^2 x}$$ $\text{B}$ is the answer.
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