Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 5 - Section 5.4 - Product-to-Sum and Sum-to-Product Formulas - Exercise Set - Page 689: 6

Answer

The required solution is $\frac{1}{2}\left[ \sin 5x-\sin x \right]$.

Work Step by Step

One of the product-to-sum formulas is $\sin \alpha \cos \beta =\frac{1}{2}\left[ \sin \left( \alpha +\beta \right)+\sin \left( \alpha -\beta \right) \right]$. So, in this question, according to the above-mentioned formula, the value of $\alpha $ is $2x$ and the value of $\beta $ is $3x$. Now, the expression can be evaluated as provided below: $\begin{align} & \sin 2x\cos 3x=\frac{1}{2}\left[ \sin \left( 2x+3x \right)+\sin \left( 2x-3x \right) \right] \\ & =\frac{1}{2}\left[ \sin 5x+\sin \left( -x \right) \right] \end{align}$ Thus, applying the even-odd identity, which is $sin(-x)=-\sin x$, the expression can be further evaluated as given below: $\frac{1}{2}\left[ \sin 5x+\sin \left( -x \right) \right]=\frac{1}{2}\left[ \sin 5x-\sin x \right]$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.