[latex]1)2sin^2-cosx-1=0[/latex] [latex]2)tgx-2ctgx+1=0[/latex] [latex]3)3cos^26x+8sin3xcos3x-4=0[/latex]

1)  2-2cos^2x-cosx-1=0 1-2cos^2x-cosx=0 2cos^2x+cosx-1=0  cosx=t    2t^2+t-1=0 t1=-1  t2=1/2 x1=П+2Пk x2=+-П/3+2Пk 2) tgx=t t-2/t+1=0   t^2+t-2=0 t1=1     x=П/4+Пk t2=-2   x=-arctg2+пk 3) 3-3sin^2(6x)-4+4sin6x=0 sin6x=t 4t-3t^2-1=0 3t^2-4t+1=0 t1=1 sin6x=1   6x=П/2+2Пk    x=п/12+Пk/3 t2=1/3  sin6x=1/3 6x=(-1)^karcsin(1/3)+Пk                                x=1/6*(-1)^k*arcsin(1/3)+Пk/6