Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 7 - Trigonometric Identities and Equations - 7.1 Fundamental Identities - 7.1 Exercises - Page 659: 72


$-\sin ^{2}\theta $

Work Step by Step

$\cos \theta \left( \cos \theta -sec\theta \right) =\cos \theta \left( \cos \theta -\dfrac {1}{\cos \theta }\right) =\cos ^{2}\theta -1=-\sin ^{2}\theta $
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