Решите уравнение sin(pi/2+x)=sin(-2x)

Cos(x) = -2sin(x)*cos(x)
cos(x)*(1 + 2sin(x)) = 0
cos(x) = 0     или     sin(x) = -1/2
x = (pi/2) + pi*k; k ∈ Z
x = (-pi/6) + 2pi*n; n ∈ Z
x = (-5pi/6) + 2pi*m; m ∈ Z