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SSC CGL 2020 PYQ — Question 31

SSC CGL Tier II - Quant - 15 Nov 2020 • Quantitative Aptitude • Q31

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If sec = ab\frac{a}{b}, b ≠ 0, then  (1 - tan2θ) / ( 2 - Sin2θ) = ?

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Correct answer: B

Explanation

The correct answer is option 2 i.e. a2 ( 2b2 - a2) / b2 ( a2 + b2)

Concept

Sec θ = H / B

Application

H/B = a/b

P = √(a2 - b2), H = a and B = b

tan2θ = (a2 - b2) / b2

sin2θ = (a2 - b2))/a2

(1 - tan2θ)/(2 - sin2θ)

[(2b2 - a2)/b2] / [(a2 + b2) / a2]

a2 ( 2b2 - a2) / b2 ( a2 + b2)