SSC CGL 2022 PYQ — Question 2

SSC CGL Tier II - Quant - 29 Jan 2022 • Quantitative Aptitude • Q2

If 7 sin2 θ + 4 cos2 θ = 5 and θ lies in the first quadrant, then what is the value of 3secθ+tanθ2cotθ−3cosθ?\frac{\sqrt{3} sec \theta + tan \theta}{\sqrt{2} cot \theta - \sqrt{3} cos \theta}?

Show answer & explanation

Correct answer: D

Explanation

The correct answer is option 4 i.e. 2(1+√2)

⇒ 7 sin2 θ + 4 cos2 θ = 5

⇒ 3 sin2 θ + 4 sin2 θ + 4 cos2 θ = 5

⇒ 3 sin2 θ = 1

⇒sinθ = 1/3\sqrt3 = P/H

B2 = 3 - 1 = 2

B = 2\sqrt2

⇒ secθ = 32\sqrt{\frac{3}{2}} , tanθ = 1/2\sqrt2 , cotθ = 2\sqrt2 and cosθ = 23\sqrt{\frac{2}{3}}

3secθ+tanθ2cotθ−3cosθ\frac{\sqrt{3} sec \theta + tan \theta}{\sqrt{2} cot \theta - \sqrt{3} cos \theta} = 3×32+122×2−3×23\frac{\sqrt3 \times \sqrt{\frac{3}{2}} + \frac{1}{\sqrt2}}{\sqrt2 \times \sqrt2 - \sqrt3 \times \sqrt{\frac{2}{3}}} = 222−2\frac{2 \sqrt2}{2-\sqrt2}

On further rationalization we get,

= 22(2+2)4−2\frac{2 \sqrt2(2+\sqrt2)}{4-2} = 2(1+√2)