Question

if sin theta + sin square theta equal to 1 then cos square theta + cos 4 theta equal to dash

Answer 1

Given,

sinθ + sin^2θ = 1

=> sinθ = 1 - sin^2θ

=> sin θ = cos^2 θ

[ °•° 1 - sin^2θ = cos^2 θ ]

=> sin^2θ = cos^4θ

[ Squaring both sides ]

=> 1 - cos^2θ = cos^4θ

[ °•° sin^2θ = 1 - cos^2θ ]

=> 1 = cos^4θ + cos^2θ

So,

cos^2θ + cos^4θ = 1

( Ηence, Found )

Hope it helps!!