Sin^2 x/2=3 cos^2 x/2
Sin^2 x/2 = 3(1 - sin^2 x/2). 4sin^2 x/2 = 3. sin^2 x/2 = 3/4. 1) sin x/2 = -\/3 / 2, x/2 = -pi/3 + 2pi*n. x = -2pi/3 + 4pi*n. 2) sin x/2 = \/3 / 2, x/2 = pi/3 + 2pi*n. x = 2pi/3 + 4pi*n.