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: 148

Answer

$\csc\theta=-3$ $\sin\theta=-\frac{1}{3}$ $ \cos\theta=\frac{2\sqrt 2}{3}$ $\sec\theta=\frac{3\sqrt 2}{4}$ $\tan\theta=-\frac{\sqrt 2}{4}$ $\cot\theta=-2\sqrt 2$

Work Step by Step

Given $\csc\theta=-3$ $\sin\theta=\frac{1}{\csc\theta}=\frac{1}{-3}=-\frac{1}{3}$ Recall: $\sin^{2}\theta+\cos^{2}\theta=1$ $\implies (-\frac{1}{3})^{2}+\cos^{2}\theta=1$ Or $\cos^{2}\theta=1-\frac{1}{9}=\frac{8}{9}$ $\implies \cos\theta=\pm\frac{\sqrt 8}{\sqrt 9}=\frac{2\sqrt 2}{3}$ (given $\cos\theta\gt0$) $\sec\theta=\frac{1}{\cos\theta}=\frac{3}{2\sqrt 2}=\frac{3\sqrt 2}{4}$ $\tan\theta=\frac{\sin\theta}{\cos\theta}=\frac{-\frac{1}{3}}{\frac{2\sqrt 2}{3}}=-\frac{1}{2\sqrt 2}=-\frac{\sqrt 2}{4}$ $\cot\theta=\frac{1}{\tan\theta}=-2\sqrt 2$
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