Trigonometry 7th Edition

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

Chapter 1 - Section 1.4 - Introduction to Identities - 1.4 Problem Set - Page 40: 50

Answer

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

Work Step by Step

Given $\sec\theta$ = 2 By reciprocal identity- $\cos\theta$ = $\frac{1}{\sec\theta}$ = $\frac{1}{2}$ We know from first Pythagorean identity that- $\sin\theta$ = ± $\sqrt (1-\cos^{2}\theta)$ Given $\sec\theta$ is positive and $\sin\theta$ is also positive, therefore $\theta$ terminates in Q I. OR $\sin\theta$ = $\sqrt (1-\cos^{2}\theta)$ substitute the given value of $\cos\theta$- $\sin\theta$= $\sqrt (1-(\frac{1}{2})^{2})$ $\sin\theta$ = $\sqrt (1-\frac{1}{4})$ $\sin\theta$ = $\sqrt (\frac{4-1}{4})$ = $\sqrt (\frac{3}{4})$ $\sin\theta$ = $\frac{\sqrt 3}{2}$ By ratio identity- $\tan\theta$ = $\frac{\sin\theta}{\cos\theta}$ Substituting the values of $\sin\theta$ and $\cos\theta$- $\tan\theta$ = $\frac{\sqrt 3/2}{ 1/2}$ = $\sqrt 3$ From reciprocal identities- $\csc\theta$ = $\frac{1}{\sin\theta}$ = $\frac{1}{\sqrt 3/2}$ = $\frac{2}{\sqrt 3}$ $\cot\theta$ = $\frac{1}{\tan\theta}$ = $\frac{1}{\sqrt 3}$
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