# If sin θ + sin2 = 1, then cos2θ + cos4θ =A. −1B. 1C. 0D. None of these

Given: sin θ + sin2 θ = 1

sin θ = 1 – sin2 θ = cos2 θ [ sin2 θ + cos2 θ = 1]……(i)

Sin2 θ = (cos2 θ)2 = cos4 θ ……(ii)

To find: cos2 θ + cos4 θ

Consider cos2 θ + cos4 θ = sin θ + sin2 θ [Using (i) and (ii)]

= 1 [Given]

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