Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 5 - Trigonometric Functions - 5.2 Trigonometric Functions - 5.2 Exercises - Page 520: 147

Answer

$\sec\theta=-4$ $\cos\theta=-\frac{1}{4}$ $ \sin\theta=\frac{\sqrt{ 15}}{4}$ $\csc\theta=\frac{4\sqrt {15}}{15}$ $\tan\theta=-\sqrt {15}$ $\cot\theta=-\frac{\sqrt {15}}{15}$

Work Step by Step

$\sec\theta=-4$ $\cos\theta=\frac{1}{\sec\theta}=\frac{1}{-4}=-\frac{1}{4}$ $\sin^{2}\theta=1-\cos^{2}\theta=1-(-\frac{1}{4})^{2}=\frac{15}{16}$ $\implies \sin\theta=\pm\sqrt {\frac{15}{16}}=\frac{\sqrt{ 15}}{4}$ (given $\sin\theta\gt0$) $\csc\theta=\frac{1}{\sin\theta}=\frac{4}{\sqrt {15}}=\frac{4\sqrt {15}}{15}$ $\tan\theta=\frac{\sin\theta}{\cos\theta}=\frac{\frac{\sqrt {15}}{4}}{-\frac{1}{4}}=-\sqrt {15}$ $\cot\theta=\frac{1}{\tan\theta}=-\frac{1}{\sqrt {15}}=-\frac{\sqrt {15}}{15}$
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