Calculus (3rd Edition)

Published by W. H. Freeman
ISBN 10: 1464125260
ISBN 13: 978-1-46412-526-3

Chapter 1 - Precalculus Review - 1.4 Trigonometric Functions - Exercises - Page 30: 11


$\dfrac{3\pi}{4}, \dfrac{7\pi}{4}$

Work Step by Step

Since $\tan{\theta} = \dfrac{\cos{\theta}}{\sin{\theta}}$ As $\tan{\theta} = -1$, we search figure 22 for points where $\cos{\theta} = -\sin{\theta}$ The two angles on the unit circle where $\cos{\theta} = -\sin{\theta}$ are $\dfrac{3\pi}{4}$ and $\dfrac{7\pi}{4}$ $\theta = \dfrac{3\pi}{4}, \dfrac{7\pi}{4}$
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