Question

Prove that si^4 0 + cos^4 0 = 1 - 2 sin^2 0 cos²0.​

Answer 1

sin^4 x + cos^4 x

= (sin^2 x)^2 + (cos^2 x)^2

[ Using a^2 + b^2 = (a + b)^2 - 2ab) ]

= (sin^2 x + cos^2 x)^2 - 2* sin^2 x* cos^2 x

= 1 - 2* sin^2 x* cos^2 x

Hence Proved