Trigonometry 7th Edition

Published by Cengage Learning
ISBN 10: 1111826854
ISBN 13: 978-1-11182-685-7

Chapter 1 - Section 1.3 - Definition I: Trigonometric Functions - 1.3 Problem Set - Page 31: 18

Answer

$\sin\theta$ = - $ \frac{1}{\sqrt 10}$ $\cos\theta$ = - $ \frac{3}{\sqrt 10}$ $\tan\theta$ = $ \frac{1}{3}$

Work Step by Step

Given $\theta$ is in standard position. Spotting a Point P on terminal side of $\theta$, in the given diagram- We find point P (-6, -2) Now, we may apply Definition I to find required trigonometric functions- We got $ x = -6, y = -2$ Therefore r= $\sqrt (x^{2} + y^{2})$ = $\sqrt ((-6)^{2} + (-2)^{2})$ = $\sqrt (36+4)$ = $\sqrt 40$ = $2\sqrt 10$ i.e. $ x = -6, y = -2,$ and $ r= 2\sqrt 10$ Applying Definition I- $\sin\theta$ =$ \frac{y}{r}$ = $ \frac{-2}{2\sqrt 10}$ = - $ \frac{1}{\sqrt 10}$ $\cos\theta$ =$ \frac{x}{r}$ =$ \frac{-6}{2\sqrt 10}$ = - $ \frac{3}{\sqrt 10}$ $\tan\theta$ =$ \frac{y}{x}$ =$ \frac{-2}{-6}$ = $ \frac{1}{3}$
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