1/21 cos (8x -π/8)≥√3/42 помогите с решением

Question

1/21 cos (8x -π/8)≥√3/42 помогите с решением

Answer 1

Cos(8x-π/8)≥√3*21/42
cos(8x-π/8)≥√3/2
2πn-π/6≤8х-π/8≤2πn+π/6, n∈Z
2πn-π/6+π/8≤8х≤2πn+π/6+π/8
2πn-π/24≤8х≤2πn+7π/24
πn/4-π/192≤х≤πn/4+7π/192
x∈[πn/4-π/192; πn/4+7π/192]