Precalculus (6th Edition) Blitzer

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

Chapter 4 - Section 4.4 - Trigonometric Functions of Any Angle - Exercise Set - Page 575: 49


$\approx 1.56$

Work Step by Step

RECALL: The following are the means on how to find the reference angle of an angle $\theta$ based on its position: (1) Quadrant I: $\theta$ (itself) (2) Quadrant II: $\pi-\theta$ (3) Quadrant III: $\theta - \pi$ (4) Quadrant IV: $2\pi-\theta$ The angle $\theta = 4.7$ is between $\pi\approx 3.14$ and $\frac{3\pi}{2}\approx 4.71$. This means that the angle is in Quadrant III. Use formula (3) to obtain: reference angle of $4.7$ = $4.7 - \pi \approx 1.56$
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