Chapter 4 - Section 4.7 - Inverse Trigonometric Functions - Exercise Set - Page 626: 32

$0.57$

Suppose $\theta =\cos^{-1}(0.57)$ This gives: $\cos \theta=\cos [\cos^{-1}(0.57)]$ The inverse property states that $\cos(\cos^{-1} a)=a $ satisfies for every $ a $ in the range $[-1,1]$ . Therefore, we have $ \cos [\cos^{-1}(0.57)]=0.57$