SSC CGL 2021 PYQ — Question 74

SSC CGL - 18 Aug 2021 - Shift 1 • Quantitative Aptitude • Q74

If 3sin2θ - cosθ - 1 = 0, 0º < θ < 90º, then what is the value of cot θ + cosecθ?

Show answer & explanation

Correct answer: C

Explanation

The correct answer is option 3 i.e. √5.

⇒ 3sin2θ - cosθ - 1 = 0

⇒ 3(1 - cos2θ) - cosθ - 1 = 0

⇒ 3 - 3cos2θ - cosθ - 1 = 0

⇒ 3cos2θ + cosθ - 2 = 0

⇒ 3cos2θ + 3cosθ - 2cosθ - 2 = 0

⇒ 3cosθ(cosθ + 1) - 2(cosθ + 1) = 0

⇒ (cosθ + 1)(3cosθ - 2) = 0

⇒ Cosθ = 2/3 , -1

Cosθ = 2/3 = B/H

By using Pythagoras theorem,

P2 = 32 - 22

P = 5\sqrt5.

⇒ cot θ + cosecθ = 2/5\sqrt5 + 3/5\sqrt5 = 5\sqrt5.