Precalculus (6th Edition)

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

Chapter 7 - Trigonometric Identities and Equations - Summary Exercises Verifying Trigonometric Identities - Exercises - Page 696: 11


$\dfrac {\sin \left( x+y\right) }{\cos \left( x-y\right) }=\dfrac {\cot y+\cot x}{1+\cot y\cot x}$

Work Step by Step

$\dfrac {\sin \left( x+y\right) }{\cos \left( x-y\right) }=\dfrac {\sin x\cos y+\cos x\sin y}{\cos x\cos y+\sin x\sin y}=\dfrac {\dfrac {\sin x\cos y+\cos x\sin y}{\sin x\sin y}}{\dfrac {\cos x\cos y+\sin x\sin y}{\sin x\sin y}}=\dfrac {\cot y+\cot x}{1+\cot y\cot x}$
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