## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson

# Chapter 6 - Analytic Trigonometry - Section 6.1 The Inverse Sine, Cosine, and Tangent Functions - 6.1 Assess Your Understanding - Page 474: 46

#### Answer

$-\dfrac{2}{3}$

#### Work Step by Step

Value of certain composite functions formula: $f(f^{-1}(x)) = \cos{(\cos^{-1}{x})}= x \hspace{25pt} -1 \leq x \leq 1$ $\therefore \cos{\left[\cos^{-1}{\left(-\dfrac{2}{3}\right)} \right]} = \boxed{-\dfrac{2}{3}}$

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