Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

The value of x, if 2 sin2 x = 2 - 3 sin x, is :

Options:

$\frac{\pi}{6}$

$\frac{\pi}{4}$

$\frac{\pi}{2}$

$\frac{\pi}{3}$

Correct Answer:

$\frac{\pi}{6}$

Explanation:

 2 sin2 x = 2 - 3 sin x

 2 sin2 x + 3 sin x - 2 = 0

 2 sin2 x + 4 sin x  -  sinx - 2 = 0

2sinx ( sinx + 2 ) -1( sinx + 2 ) = 0

( 2sinx -1 )(sinx + 2 ) = 0

Either ( 2 sinx - 1 = 0 )  OR   ( sinx + 2 = 0 )

{ sinx + 2 = 0 is not possible }

So, 2 sinx - 1 = 0

sinx = \(\frac{1 }{2}\)

{ we know,  sin30º = \(\frac{1 }{2}\) }

So, x = 30º

= \(\frac{π}{6}\)