Решить уравнение cos(1,5п-2x)-cosx=0

Cos(1.5π-2x) = -sin2x
-sin2x - cosx = 0
-2sinxcosx - cosx =0
-cosx*(2sinx + 1) =0
cosx=0, x = π/2+πn
2sinx +1 =0, sinx=-1/2, x= (-1)^k+1 *π/6 + πk

Вот полностью напиши!
sin2x-sin(π/2-x)=0
2sin(3x/2-π/4)cos(x/2+π/4)=0
sin(3x/2-π/4)=0
3x/2-π/4=πn
3x/2=π/4+πn
x=π/6+2πn/3
cos(x/2+π/4)=0
x/2+π/4=π/2+πn
x/2=π/4+πn
x=π/2+2πn