SSC CGL 2022 PYQ — Question 57

The correct answer is option 1 i.e. 0.

Formula used:

Cos3θ = 3cos θ - 4 cos³ θ       ---- (1)

Calculations:

We know that, sin θ = 1/2 when θ = 30

Using equation (1), we get

⇒ 3cos θ - 4 cos³ θ = Cos3θ

⇒ cos 3(30) = cos 90 = 0