Cos(x/4-пи/6)=-1/2 Помогите плиз!!!!

Question

Cos(x/4-пи/6)=-1/2 Помогите плиз!!!!

Answer 1

Cos(x/4-π/6)=-1/2
x/4-π/6=2π/3    x/4=2π/3+π/6=5π/6  x₁=10π/3
x/4-π/6=4π/3    x/4=4π/3+π/6=3π/2  x₂=6π.
Ответ: х₁=10π/3  х₂=6π.