cos x/3=-1/2 помогииииите

Question

cos x/3=-1/2 помогииииите

Answer 1

x/3  = ±arccos (-1/2) + 2πn

x/3 = ±2π/3 + 2πn, n∈Z

x = ±2π + 6πn,n∈Z

Answer 2

х/3=+-2п/3+2п*н

х=+-2п+6п*н