Cos 2 3x 0. Cos2x-3cosx+2 0. 1/Cos2x-3/cosx+2 0. 3cosx-cos^2x=0. Cos2x-3cos(-x)+2=0. 3cos^2 2x + 7sin2x - 3 = 0. 3sin 2 x+7cos2x-3=0. Cos2x-3sin(-x)-2=0. Sin2x+2cos2x=0. 2cos(x/2-п/6)=√3. 3sin2x 2sinxcosx+cos2x. Sin2x+2sinxcosx-3cos2x 0. Решение уравнения 2sin2x -3sinxcosx+cos2x=0