Precalculus (6th Edition) Blitzer

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

Chapter 5 - Section 5.5 - Trigonometric Equations - Exercise Set - Page 705: 134


$t=6k+1\ sec$ and $t=6k+5\ sec$

Work Step by Step

Step 1. Given the model function $d=-4\ cos(\frac{\pi}{3}t)$, at $d=-2\ in$, we have $-4\ cos(\frac{\pi}{3}t)=-2$ or $cos(\frac{\pi}{3}t)=0.5$ Step 2. The general solutions for the above equation are $\frac{\pi}{3}t=2k\pi+\frac{\pi}{3}$ and $\frac{\pi}{3}t=2k\pi+\frac{5\pi}{3}$ or $t=6k+1\ sec$ and $t=6k+5\ sec$, where $k$ is an integer.
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