Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 5 - Trigonometric Functions - Section 5.3 Properties of the Trigonometric Functions - 5.3 Assess Your Understanding - Page 418: 52

Answer

$\sin{\theta} =- \dfrac{\sqrt{15}}{4}$ $\tan{\theta}=\sqrt{15}$ $\csc{\theta} =-\dfrac{4 \sqrt{15} }{15}$ $\sec{\theta} =-4$ $\cot{\theta} =\dfrac{\sqrt{15}}{15}$

Work Step by Step

$\tan{\theta} = \dfrac{\sin{\theta}}{\cos{\theta}} >0$ Since $\cos{\theta} \lt 0$, then $\sin{\theta}$ must be negative. Thus, $\sin{\theta} = -\sqrt{1-\cos^2 {\theta}}$ $\sin{\theta} = -\sqrt{1-\left(-\dfrac{1}{4} \right)^2}= - \dfrac{\sqrt{15}}{4}$ $\tan{\theta}= \dfrac{\sin{\theta}}{\cos{\theta}}$ $\tan{\theta}= \dfrac{- \dfrac{\sqrt{15}}{4}}{-\dfrac{1}{4}} = \sqrt{15}$ $\csc{\theta} = \dfrac{1}{\sin{\theta}}$ $\csc{\theta} = \dfrac{1}{- \dfrac{\sqrt{15}}{4}}= -\dfrac{4 \sqrt{15} }{15}$ $\sec{\theta} = \dfrac{1}{\cos{\theta}}$ $\sec{\theta} = \dfrac{1}{-\dfrac{1}{4}} = -4$ $\cot{\theta} = \dfrac{1}{\tan{\theta}}$ $\cot{\theta} = \dfrac{1}{\sqrt{15}} = \dfrac{\sqrt{15}}{15}$
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