Тригонометрическое уравнение
2cos(3x+π/3)=1 cos(3x+π/3)=1/2 3x+π/3=-π/3+2πn U 3x+π/3=π/3+2πk 3x=-2π/3+2πn U 3x=2πk x=-2π/9+2πn/3,n∈z U x=2πk/3,k∈z