1)2cos 2x = 1
2) 2 sin x/2 - 1 = 0

1. 2cosx=1cos2x=1/22x=+-arccos(1/2)+2πn, n∈Z2x=+-π/3+2πn, n∈x | :2x=+-π/6+πn, n∈Z2. 2sin(x/2)-1=02sin(x/2)=1sin(x/2)=1/2  n∈Zn∈Z  |*2n∈Z