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 - Chapter Review - Review Exercises - Page 458: 22

Answer

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

Work Step by Step

Given $sec\theta=3$ and $\theta$ is in quadrant IV, let $r=3, x=1$, we have $y=-\sqrt {(3)^2-(1)^2}=-2\sqrt {2}$, thus: $sin\theta=\frac{y}{r}=-\frac{2\sqrt {2}}{3}$, $cos\theta=\frac{x}{r}=\frac{1}{3}$, $tan\theta=\frac{y}{x}=-2\sqrt {2}$, $cot\theta=\frac{1}{tan\theta}=-\frac{\sqrt {2}}{4}$, $csc\theta=\frac{1}{sin\theta}=-\frac{3\sqrt {2}}{4}$.
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