Решите неравенство cos(3x-2п/3)>=-1/2

Question

Решите неравенство cos(3x-2п/3)>=-1/2

Answer 1

4π/3+2πn≤3x-2π/3≤8π/3+2πn
2π+2πn≤3x≤10π/3+2πn
2π/3+2πn/3≤x≤10π/9+2πn/3,n∈z