1) 2sinx = 1
sinx = 1/2
x = (-1)^n * arcsin1/2 + pi*n
x = (-1)^n * pi/6 + pi*n, n € Z.
2) sinx/2 = 1
x/2 = pi/2 + 2pi*n
x = pi + 4pi*n, n € Z.
3) 2sinx/2 = 1
sinx/2 = 1/2
x/2 = (-1)^n * arcsin1/2 + pi*n
x/2 = (-1)^n * pi/6 + pi*n
x = (-1)^n * pi/3 + 2pi*n, n € Z