Question

3sin^2x-3sin x*cos x-4 cos x=-2

Answer 1

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