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SSC CGL 2016 PYQ — Question 11

SSC CGL Tier II Quant - 30/11/2016 • Quantitative Aptitude • Q11

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If tan4θ + tan2θ = 1 then the value of cos4θ + cos2θ is?

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Correct answer: C

Explanation

The correct answer is option 3 i.e. 1 

tan4θ + tan2θ = 1

⇒ tan2θ(tan2θ + 1) = 1

⇒ tan2θ sec2θ = 1

⇒ (sec2θ - 1) (sec2θ) = 1

⇒ sec4θ - sec2θ = 1

⇒ cos4θ + cos2θ = 1