SSC CGL 2024 PYQ — Question 69

SSC CGL - 13 Sep 2024 - Shift 3 • Quantitative Aptitude • Q69

If tan(x)sec(x)=12{tan(x)\over sec(x)} = {1\over 2}, then the value of (sinx + cos x)2 is _________.

Show answer & explanation

Correct answer: B

Explanation

The correct answer is Option 2 i.e. 2+322+\sqrt3 \over2.

tan(x)sec(x)=12{tan(x)\over sec(x)} = {1\over 2}

⇒ sin(x)cos(x)1cos(x)=12{{sin(x)\over cos(x)}\over {1\over cos(x)}} = {1\over 2}

⇒ sin(x)=12=PHsin(x) = {1\over 2} = {P\over H} 

By Pythagoras theorem

⇒ H2 = B2 + P2

⇒ 22 = B2 + 12

⇒ B2 = 4 - 1

⇒ B2 = 3

⇒ B = 3\sqrt3

so, cos(x) = BHB\over H = 32\sqrt3 \over 2

Now, (sinx + cos x)2 = sin2x + cos2x + 2sinx.cosx

⇒ 1 + 2 × 12\frac 1 2  × 32\sqrt3 \over 2 = 1 + 32\sqrt3 \over 2 = 2+322+\sqrt3 \over2