Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 5 - Section 5.2 - Trigonometric Functions of Real Numbers - 5.2 Exercises - Page 418: 69

Answer

$\cos{t} =-\dfrac{\sqrt{15}}{4}$ $\tan{t}= \dfrac{\sqrt{15}}{15}$ $\csc{t} =-4$ $\sec{t} =\dfrac{4\sqrt{15}}{15}$ $\cot{t} =\sqrt{15}$

Work Step by Step

$\because \sec{t} <0 \hspace{20pt} \therefore \cos{t} <0$ $\cos{t} = - \sqrt{1-\sin^2{t}} \\ = - \sqrt{1-\left(\dfrac{-1}{5}\right) ^2} = -\dfrac{\sqrt{15}}{4}$ $\tan{t}= \dfrac{\sin{t}}{\cos{t}} = \dfrac{\sqrt{15}}{15}$ $\csc{t} = \dfrac{1}{\sin{t}} = -4$ $\sec{t} = \dfrac{1}{\cos{t}} = \dfrac{4\sqrt{15}}{15}$ $\cot{t} = \dfrac{1}{\tan{t}} = \sqrt{15}$
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