Trigonometric Equations Question 71

Question: The most general value of $ \theta $ which will satisfy both the equations $ \sin \theta =-\frac{1}{2} $ and $ \tan \theta =\frac{1}{\sqrt{3}} $ is

[MNR 1980; MP PET 1989; DCE 1995]

Options:

A) $ n\pi +{{(-1)}^{n}}\frac{\pi }{6} $

B) $ n\pi +\frac{\pi }{6} $

C) $ 2n\pi \pm \frac{\pi }{6} $

D) None of these

Show Answer

Answer:

Correct Answer: D

Solution:

  • $ \sin \theta =-\frac{1}{2}=\sin ( -\frac{\pi }{6} )=\sin ( \pi +\frac{\pi }{6} ) $ $ \tan \theta =\frac{1}{\sqrt{3}}=\tan ( \frac{\pi }{6} )=\tan ( \pi +\frac{\pi }{6} )\Rightarrow \theta =( \pi +\frac{\pi }{6} ) $ Hence general value of $ \theta $ is $ 2n\pi +\frac{7\pi }{6} $ .