SSC CGL 2024 PYQ — Question 56

SSC CGL - 13 Sep 2024 - Shift 1 • Quantitative Aptitude • Q56

If 11−sinθ+11+sinθ=4secθ,(0<θ<90){{1} \over 1 - sinθ} + {{1} \over 1 + sinθ} = 4secθ, (0 < θ < 90 )  then find the valur of ( cotθ + cosecθ ) is :

Show answer & explanation

Correct answer: A

Explanation

The correct answer is option 1 i.e.  3{ \sqrt{3} }

let's, 11−sinθ+11+sinθ=4secθ,(0<θ<90){{1} \over 1 - sinθ} + {{1} \over 1 + sinθ} = 4secθ, (0 < θ < 90 )

⇒ (1+sinθ)+(1−sinθ)(1−sinθ)(1+sinθ)=4secθ{{(1 + sin \theta) + (1 - sin\theta)} \over {(1 - sin\theta)(1 + sin\theta)}} = {4 sec\theta}

⇒ 2(1−sin2θ)=4cosθ{2\over {(1 - sin^2\theta)}} = {4 \over cos\theta}

⇒ 4 cos2θ = 2cosθ

⇒ cosθ = 1/2

⇒ θ = 60°

then, (cot60° + cosec60°) 

 ⇒ 13+23{ 1\over \sqrt{3}} + {2 \over \sqrt{3}}

⇒ 333 \over \sqrt{3} = 3{ \sqrt{3} }

​So the expected answer is 3{ \sqrt{3} }.