SSC CHSL 2021 PYQ — Question 51

SSC CHSL - 5 Aug 2021 - Shift 2 • Quantitative Aptitude • Q51

If cosθ  =p2−1p2+1,0={{p^2-1} \over p^2+1},0º < θ < 90º, then cosecθ is equal to:

Show answer & explanation

Correct answer: B

Explanation

The correct answer is Option 2 i.e. 1+P22P{{1+P^2} \over 2P}

Given:

  cosθ  =p2−1p2+1={{p^2-1} \over p^2+1}

Formula USed:

cosθ = BaseHypotenuseBase \over Hypotenuse

Pythagoras theorem, H2 = P2 + B2

cosecθ = HypotenusePerpendicularHypotenuse \over Perpendicular

Explanation:

Accordin to the given question,

B = p2 - 1 and H = p2 + 1

So, P2 = H2 - B2 ⇒ P2 = (p2 + 1)2 - (p2 - 1)2

⇒ P2 = 4p2

⇒ P = 2p

Now putting this in the formula of cosecθ, we get

cosecθ = p2+12p{p^2 + 1} \over 2p

Hence the required answer is p2+12p{p^2 + 1} \over 2p .