SSC CGL 2021 PYQ — Question 67

SSC CGL - 20 Aug 2021 - Shift 2 • Quantitative Aptitude • Q67

If 2cos2 θ\theta - 5 cos θ\theta + 2 = 0, 0º < θ\theta < 90º, then the value of (sec θ\theta + tan θ\theta) is:

Show answer & explanation

Correct answer: A

Explanation

The correct answer is option 1 i.e.  2 + 3\sqrt{3}.

⇒ 2cos2 θ\theta - 5 cos θ\theta + 2 = 0

⇒ 2cos2 θ\theta - 4 cos θ\theta - cosθ\theta + 2 = 0

⇒ 2cosθ\theta(cosθ\theta - 2) -1(cosθ\theta - 2) = 0

⇒ (cosθ\theta - 2)(2cosθ\theta - 1)

⇒ cosθ\theta = 1/2 and 2

cosθ\theta cannot be beyond 1 so 2 is not possible.

cosθ\theta = cos60

θ\theta = 60.

= Now sec60 + tan60

= 2 + 3\sqrt{3}.