Answer
$-\frac{7}{25}$
Work Step by Step
Step 1. Letting $tan^{-1}(\frac{4}{3})=x$, we have $tan(x)=\frac{4}{3}, sin(x)=\frac{4}{5}$
Step 2. We have $cos(2x)=1-2sin^2(x)=1-2(\frac{4}{5})^2=-\frac{7}{25}$
Precalculus (10th Edition)
by Sullivan, Michael
Published by
Pearson
ISBN 10:
0-32197-907-9
ISBN 13:
978-0-32197-907-0
Chapter 7 - Analytic Trigonometry - Chapter Review - Review Exercises - Page 506: 63
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