Решите уравнение cos(2x)=sin(6x)

Но cos(2*(2/9π+4/9π)) не равен sin (6*(2/9π+4/9π))

cos 2x=sin (π/2-2x)sin (π/2-2x) =sin6xлибо π/2-2x=6x+2πn  8x=π/2- 2πn   x=π/16-π/4 n    n∈Zлибо π/2-2x+6x=π+2πm      9/2x=π+2πm      x=2/9π+4/9πm   m∈Z