Cos (1/2)=1 cos2x-3cosx=0 sin (3x-П/4)=0

2sin^2x+3cosx-3=0 2 (1-cos^2x)+3cosx-3=0 2-2cos^2x+3cosx-3=0 2cos^2x-3cosx+1=0 Замена cosx=t, t [-1; 1] 2t^2-3t+1=0 D=9-8=1 t1,2=(3+-1) /4 t1=1/2 t2=1 cosx=1/2 x=+-pi/3+2pik, k Z cosx=1 x=2pik, k Z Ответ: x=+-pi/3+2pik, k Z x=2pik, k Z