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SSC CGL 2020 PYQ — Question 2

SSC CGL Tier II - Quant - 18 Nov 2020 • Quantitative Aptitude • Q2

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If α + β = 90º and α =  2β, then the value of 3 cos2α - 2 sin2 β is equal to:

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Correct answer: C

Explanation

The correct answer is option 3 i.e. 14\frac{1}{4}

Here it is given that,

α + β = 90º and α =  2β

2β + β = 90

β = 30°.

α  = 60°

3 cos2α - 2 sin2 β = 3 cos260 - 2 sin2 30

= 3 × 1/4 - 2 × 1/4 = 1/4.