sin²(x/2)=3*(cos²(x/2))
Для упрощения, пусть х/2=t ⇒
sin²t=3*cos²t
sin²t=3-3*sin²t
4*sin²t=3 |÷4
sin²t=3/4
sint=√(3/4)
sint=+/-√3/2
t₁=π/3 ⇒ x/2=π/3+2πn x₁=2π/3+2πn
t₂=2π/3 ⇒ x/2=2π/3+2πn x₂=4π/3+2πn
t₃=4π/3 ⇒ x/2=4π/3+2πn x₃=8π/3+2
t₄=5π/3 ⇒ x/2=5π/3+2πn x₄=10π/3+2πn