Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

If $3 \sin ^2 \theta+4 \cos \theta-4=0,0^{\circ}<\theta<90^{\circ}$, then the value of $\left(cosec^2 \theta+\cot ^2 \theta\right)$ is

Options:

$\frac{5}{4}$

$\frac{25}{3}$

$\frac{4}{3}$

$\frac{17}{9}$

Correct Answer:

$\frac{5}{4}$

Explanation:

3 sin2θ + 4 cosθ - 4 = 0

3 ( 1 - cos2θ) + 4 cosθ - 4 = 0

3cos2θ - 4 cosθ + 1 = 0

on solving ,

cosθ = \(\frac{1}{3}\)

By using pythagoras theorem ,

P2 + B2 = H2

P2 + 12 = 32

P = 2√2

Now , ( cosec2θ + cot2θ)

= (\(\frac{3}{2√2}\))2 + (\(\frac{1}{2√2}\))2 

= \(\frac{9}{8}\) + \(\frac{1}{8}\)

= \(\frac{5}{4}\)