3cos^2x/2-3sin^2x^2-2sinx/2cosx/2-sin^2x/2-cos^2x/2=0
cos^2x/2-2sin^2x/2-sinx/2cosx/2=0
1-2tg^2x/2-tgx/2=0 cosx/2 неравен 0
tgx/2=t
2t^2+t-1=0
t1=-1
t2=1/2
x=2arctg(1/2)+2Пk
x=-П/2+2Пk
