Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 7 - Section 7.1 - Trigonometric Identities - 7.1 Exercises - Page 543: 64

Answer

$\dfrac{\sin x+\cos x}{\sec x+\csc x}=\sin x\cos x$

Work Step by Step

$\dfrac{\sin x+\cos x}{\sec x+\csc x}=\sin x\cos x$ On the left side of the equation, replace $\sec x$ by $\dfrac{1}{\cos x}$ and $\csc x$ by $\dfrac{1}{\sin x}$: $\dfrac{\sin x+\cos x}{\dfrac{1}{\cos x}+\dfrac{1}{\sin x}}=\sin x\cos x$ Evaluate $\dfrac{1}{\cos x}+\dfrac{1}{\sin x}$: $\dfrac{\sin x+\cos x}{\dfrac{\sin x+\cos x}{\sin x\cos x}}=\sin x\cos x$ Evaluate the division and the identity will be proved: $\dfrac{\sin x\cos x(\sin x+\cos x)}{\sin x+\cos x}=\sin x\cos x$ $\sin x\cos x=\sin x\cos x$
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