If sin θ + sin2θ = 1, then the value of cos2θ + cos4θ is equal to:
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Correct answer: C
Explanation
The correct answer is option 3 i.e. 1
⇒ sin θ + sin2θ = 1
⇒ sin θ = 1 - sin2θ
⇒ sin θ = cos2θ ......(1)
⇒ cos2θ + cos4θ can be written as,
⇒ sinθ + sin2θ
⇒ 1.