SSC CHSL 2024 PYQ — Question 61

SSC CHSL - 10 July 2024 - Shift 1 • Quantitative Aptitude • Q61

If tan A = 2\sqrt2 - 1 then find the value of sinAcosA + tanA.

Show answer & explanation

Correct answer: B

Explanation

The correct answer is option 2 i.e. 52−445\sqrt{2}-4\over4.

tan A = P/B = 2\sqrt2 - 1 

P =  2\sqrt2 - 1 , B = 1

By using the Pythagoras theorem

H2 = P2 + B2

⇒ H2 = (2\sqrt2 - 1)2 + 12

⇒ H2 = 4−22\sqrt{4-2\sqrt2} 

sinAcosA + tanA = 2−14−22×14−22+2−1\frac{\sqrt2-1}{\sqrt{4-2\sqrt2}}\times\frac{1}{\sqrt{4-2\sqrt2}}+\sqrt2-1

= 2−14−22+2−1\frac{\sqrt2-1}{ 4-2\sqrt2}+\sqrt2-1

= 2−122(2−1)+2−1\frac{\sqrt2-1}{ 2\sqrt2(\sqrt2-1)}+\sqrt2-1

= 122+2−1\frac{1}{2\sqrt2}+\sqrt2-1

= 122×22+2−1\frac{1}{2\sqrt2}\times\frac{\sqrt2}{\sqrt2}+\sqrt2-1

= 2+42−44\frac{\sqrt2+4\sqrt2-4}{4}

= 52−445\sqrt{2}-4\over4