Cos(x+π/6)<=-1/2 Помогите решить !!!!

Question

Cos(x+π/6)<=-1/2<br> Помогите решить !!!!

Answer 1

Cos(x+π/6)≤-1/2 
t=x+π/3
cost≤-1/2
2π/3+2πn≤t≤ 4π/3+2πn; n-celoe
2π/3+2πn≤ x+π/3≤  4π/3+2πn
2π/3-π/3≤ x≤  4π/3-π/3+2πn
π/3+2πn ≤  x  ≤   π+2πn