(2cosx-1)*(cos2x+1)=0

Question

(2cosx-1)*(cos2x+1)=0

Answer 1

1) cos x = 1/2                        2) cos 2*x = -1

x = ± π/3 + 2 * π * n                   2*x = π + 2 * π * n

                                                 x = π/2 + π * n