Question

sin^4x + cos^4x=1 - 1/2sin^2x

Answer 1

this is ur answer check

Answer 2

Step-by-step explanation:

Suppose sinx=a and cosx=b

Now, sin4x+cos4x

⟹a4+b4

⟹(a2)2+(b2)2

⟹(a2+b2)2−2a2b2

∵(x+y)2=x2+y2+2xy

Now, put sinx=a and cosx=b

⟹sin4x+cos4x

⟹(sin2x+cos2x)2−2sin2xcos2x

⟹(1)2−2sin2xcos2x

⟹1−2sin2xcos2x