Trigonometry 7th Edition

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

Chapter 6 - Section 6.2 - More on Trigonometric Equations - 6.2 Problem Set - Page 332: 29

Answer

$\theta=\{30^o,90^o\}$

Work Step by Step

$\sqrt{3}sin(\theta)-cos(\theta)=\sqrt{3}$ $\sqrt{3}sin(\theta)-\sqrt{3}=cos(\theta)$ $(\sqrt{3}sin(\theta)-\sqrt{3})^2=(cos(\theta))^2\;\;\;\;\;\;\;\;\;\;$ $3sin^2(\theta)-6sin(\theta)+3=cos^2(\theta)\;\;\;\;\;\;\;\;\;\;\;\;$ $3sin^2(\theta)-6sin(\theta)+3=1-sin^2(\theta)$ $4sin^2(\theta)-6sin(\theta)+2=$ $2sin^2(\theta)-3sin(\theta)+1=$ $sin(\theta)=\frac{-b \pm \sqrt{b^2-4ac}}{2a}=\frac{-(-3) \pm \sqrt{(-3)^2-4(2)(1)}}{2(2)}=1,\frac{1}{2}$ $sin(\theta)=1$ $\theta= sin^{-1}(1)$ $\theta=90^o\;\;\;\;\;\;\;\;\;\;\;\;\;\;$ $sin(\theta)=\frac{1}{2}$ $\theta=sin^{-1}(\frac{1}{2})$ We know $ sin(\theta) $ is positive in quadrant $I$ and quadrant $II$ $\theta=30^o\;\;\;\;\;\;\;\;or\;\;\;\;\;\;\;\;\theta=180^o-30^o$ $\theta=30^o\;\;\;\;\;\;\;\;\;\;\;\;\;\;or\;\;\;\;\;\;\;\;\;\;\;\theta=150^o\;\;\;$ Reduce $\theta=\{30^o,90^o\}$
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