Trigonometric Equations Question 28
Question: The number of values of $ \theta $ in
[0, 2p] satisfying the equation $ 2{{\sin }^{2}}\theta =4+3 $ $ \cos \theta $ are [MP PET 1989]
Options:
A) 0
B) 1
C) 2
D) 3
Show Answer
Answer:
Correct Answer: A
Solution:
- $ 2-2{{\cos }^{2}}\theta =4+3\cos \theta $
$ \Rightarrow $ $ 2{{\cos }^{2}}\theta +3\cos \theta +2=0 $
$ \Rightarrow $ $ \cos \theta =\frac{-3\pm \sqrt{9-16}}{4} $ , which is imaginary, hence no solution.
BETA
