Algebra and Trigonometry 10th Edition

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

Chapter 7 - 7.2 - Verifying Trigonometric Identities - 7.2 Exercises - Page 520: 12


The trigonometric Identity is verified. $cos^2β-sin^2β=2~cos^2β-1$

Work Step by Step

$sin^2β+cos^2β=1~~$ (Pythagoren Identity) $cos^2β-1=-sin^2β$ Now: $cos^2β-sin^2β=cos^2β+cos^2β-1=2~cos^2β-1$
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