1) sin 4x=sin 2x

2) sin 2x=cos^2 x

1) 2 sin 2x cos 2x = sin 2x;

sin2x (2 cos2x - 1) = 0;

sin2x=0; ⇒2x = pik; x = pk/2; k-Z,

2 cos2x - 1 = 0;

cos 2x = 1/2;

2x = + - pi/3 + 2pin;

x = + - pi/6 + pin; n-Z.

2) 2 sinxcosx=cos^2x

2 sinxcosx - cos^2x = 0;

cosx (2 sinx - cosx) = 0;

cosx=0; ⇒x=pi/2 + pik; k-Z.

2 sinx - cos x=0;

2 sinx = cos x; / 2 cos x≠0;

tgx=1/2;

x = arctg1/2 + pin; n-Z