3sin^2x-3sinx*cosx-4cosx+2=0 5sin^2x-3sinx*cosx-4cosx+2cos^2x=0 /cosx 5tg^2x-3tgx-2=0 tgx=t D=49 x1=-0.4; tgx=-0.4 x=arctg(-2/5)+pik x2=1; tgx=1 x=pi/4+pik