1 + sin^2(x) = 1 - sin^2(x) + sin(x)
2sin^2(x) - sin(x) = 0
sin(x) * (2sin(x) - 1) = 0
1) sin(x) = 0
x = pi + pi*n, n ∈ Z
2) 2 sin(x) - 1 = 0; sin(x) = 1/2;
x = (-1)^n + pi/6 + pi*n, n ∈ Z
