SSC CGL 2022 PYQ — Question 71

The correct answer is Option 3 i.e. $\cos(\frac\pi3 +x)$

Formula used:

cos(a + b) = cos a.cos b - sin a.sin b           ---- (1)

Calculations:

⇒ ${\cos x- \sqrt{3}\sin x \over 2}$

It can be written as

⇒ 1/2(cosx) - √3/2(sinx)

We know that cos π/3 = 1/2 and sin π/3 = √3/2

⇒ cos(π/3)cosx - sin(π/3)sinx

Using equation (1), we get

⇒ cos(π/3 + x)