sin4x+cos4x=1-2sin2xcos2x
LHS- sin4x + cos4x
= (sin2x)2 + (cos2x)2
= (sin2x + cos2x)2 - 2sin2xcos2x {since a2 +b2 = (a+b)2 - 2ab}
= 12 - 2sin2xcos2x {since sin2x +cos2x = 1}
= 1 - 2sin2xcos2x
= RHS
sin4x+cos4x=1-2sin2xcos2x
LHS- sin4x + cos4x
= (sin2x)2 + (cos2x)2
= (sin2x + cos2x)2 - 2sin2xcos2x {since a2 +b2 = (a+b)2 - 2ab}
= 12 - 2sin2xcos2x {since sin2x +cos2x = 1}
= 1 - 2sin2xcos2x
= RHS