Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 7 - Section 7.3 - Double-Angle, Half-Angle, and Product-Sum Formulas - 7.3 Exercises - Page 561: 60



Work Step by Step

Use the first Product-to-Sum Formula, $\sin u\cos v=\frac{1}{2}[\sin(u+v)+\sin(u-v)]$. $11\sin\frac{x}{2}\cos\frac{x}{4}$ $=11\times\frac{1}{2}[\sin(\frac{x}{2}+\frac{x}{4})+\sin(\frac{x}{2}-\frac{x}{4})]$ $=\frac{11}{2}(\sin\frac{3x}{4}+\sin\frac{x}{4})$
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