sin^2x-cos^2x=0

1-cos2x-1-cos2x=0

cos2x=0

x=p/4+pn/2

sin^2(pi+x) +cos^2(2pi-x) = 0

-sin^2 x+(1-sin^2 x) =0

-sin^2 x +1-sin^2 x =0

-2sin^2 x = -1

2sin^2 x =1

sin^2 x =1/2

sin x = +-sqrt (1/2)

x = arcsin +2Pi*n, n э R

x = - arcsin +2Pi*n, n э R