Algebra and Trigonometry 10th Edition

Published by Cengage Learning
ISBN 10: 9781337271172
ISBN 13: 978-1-33727-117-2

Chapter 7 - 7.5 - Multiple-Angle and Product-to-Sum Formulas - 7.5 Exercises - Page 548: 17

Answer

$6~cos^2x-3=3~cos~2x$

Work Step by Step

$sin^2x+cos^2x=1$ $cos^2x-1=-sin^2x$ Use: $cos~2x=cos^2x-sin^2x=2~cos^2x-1$ $6~cos^2x-3=3(2~cos^2x-1)=3~cos~2x$
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