Cosx≥1/2
x∈[-π/3+2πn;π/3+2πn,n∈z]
2sin(x+π/6)≤√3
sin(x+π/6)≤√3/2
2π/3+2πn≤x+π/6≤7π/3+2πn
2π/3-π/6+2πn≤x≤7π/3-π/6+2πn
π/2+2πn≤x≤13π/6+2πn,n∈z
x∈[π/2+2πn;13π/6+2πn,n∈z]
2cos(x-π/3)>-√2
cos(x-π/3)>-√2/2
-3π/4+2πn-3π/4+π/3+2πn-5π/12+2πnx∈(-5π/12+2πn;13π/12+2πn,n∈z)