Precalculus (6th Edition) Blitzer

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

Chapter 5 - Section 5.3 - Double-Angle, Power-Reducing, and Half-Angle Formulas - Exercise Set - Page 682: 98


The graphs do not appear to coincide.

Work Step by Step

The graphs of $y=\cos\frac{x}{2}$ (the red graph) and $y=\frac{1}{2} \cos x$ (the blue graph) do not coincide. For $x=\pi$ we have$$\cos \frac{\pi }{2}=0 \neq -\frac{1}{2} = \frac{1}{2} \cos \pi .$$
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