2)cos(x+π/3)=1/2<=>sin(π/6-x)=1/2
π/6-x=2πn+arcsin(1/2), n€Z
{π/6-x=2πn+5π/6, n€Z или
π/6-x=2πk+π/6, k€Z}
{-x=2πn+2π/3, n€Z или
-x=2πk, k€Z}
{x=-2πn-2π/3, n€Z или
x=-2πk, k€Z}
