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प्रश्न
If sin θ + sin2 θ = 1, then cos2 θ + cos4 θ =
विकल्प
−1
1
0
None of these
उत्तर
Given:
`sin θ+sin^2θ=1`
`⇒ 1-sin^2θ= sin θ`
Now,
`cos^2θ+cos^4θ`
`= cos^2 θ+cos^2θcos^2θ`
=` cos^2θ+(1-sin^2θ)(1-sin^2θ)`
`=cos^2θ+sinθ sinθ`
`=cos^2 θ+sin^2θ`
`=1`
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