Calculus, 10th Edition (Anton)

Published by Wiley
ISBN 10: 0-47064-772-8
ISBN 13: 978-0-47064-772-1

Appendix B - Trigonometry Review - Exercise Set B - Page A25: 45

Answer

Ans. a. 4√5/9, b. -1/9

Work Step by Step

Given:- cosθ=2/3 a. Sin2θ=2cosθsinθ =$2\sqrt {1-cos^2θ}$cosθ =2$\sqrt {1-4/9}$×2/3 =4√5/9 Ans. b. $Cos2θ=cos^2θ-sin^2θ$ =$cos^2θ-1+cos^2θ$ =$2cos^2θ-1$ =2×4/9-1 =-1/9 Ans.
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