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: 141

Answer

$\sin\theta=\frac{\sqrt {5}}{7}$ $\cos\theta=\frac{2\sqrt {11}}{7}$ $\csc\theta=\frac{7\sqrt 5}{5}$ $\sec\theta=\frac{7\sqrt {11}}{22}$ $\tan\theta=\frac{\sqrt {55}}{22}$ $\cot\theta=\frac{2\sqrt {55}}{5}$

Work Step by Step

$\sin\theta=\frac{\sqrt {5}}{7}$ Recall that $\sin^{2}\theta+\cos^{2}\theta=1$ $\implies\cos^{2}\theta=1-\sin^{2}\theta=1-(\frac{\sqrt 5}{7})^{2}=\frac{44}{49}$ $\cos\theta=\pm\sqrt {\frac{44}{49}}=\frac{2\sqrt {11}}{7}$ ($\cos\theta\gt0$ in quadrant I) $\csc\theta=\frac{1}{\sin\theta}=\frac{7}{\sqrt {5}}=\frac{7\sqrt 5}{5}$ $\sec\theta=\frac{1}{\cos\theta}=\frac{7}{2\sqrt {11}}=\frac{7\sqrt {11}}{22}$ $\tan\theta=\frac{\sin\theta}{\cos\theta}=\frac{\frac{\sqrt 5}{7}}{\frac{2\sqrt {11}}{7}}=\frac{\sqrt 5}{2\sqrt {11}}=\frac{\sqrt {55}}{22}$ $\cot\theta=\frac{1}{\tan\theta}=\frac{22}{\sqrt {55}}=\frac{22\sqrt {55}}{55}=\frac{2\sqrt {55}}{5}$
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