# Chapter 7 - Trigonometric Identities and Equations - 7.7 Equations Involving Inverse Trigonometric Functions - 7.7 Exercises - Page 728: 5

A

#### Work Step by Step

A. From the definition of arccos, x is the number from $[0, \pi]$ for which $\cos x=-1.$ $\pi\in [0, \pi]$and $\cos\pi=-1.$ so $\pi$ is the solution. B. From the definition of arccos, x is the number from $[0, \pi]$ for which $\cos x=$+$1.$ $\pi\in [0, \pi]$and $\cos\pi=-1.$ so $\pi$ is NOT the solution. C. From the definition of arcsin, x is the number from $[-\displaystyle \frac{\pi}{2}, \displaystyle \frac{\pi}{2}]$ for which $\sin x=-$1. $\pi\not\in [-\displaystyle \frac{\pi}{2}, \displaystyle \frac{\pi}{2}]$ so $\pi$ is NOT the solution.

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