Sin2(x+П\3)=1+cos2(x+П\3)
sin²(x+π/3)=1+cos²(x+π/3)
cos²(x+π/3)-sin²(x+π/3)=-1
cos(2x+2π/3)=-1
2x+2π/3=π+2πn , n∈Z
2x=π-2π/3+2πn
2x=π/3+2πn
x=π/6+πn , n∈Z