2sin^2x - 3sin2x -4cos2x=4 нужно, .

2sin²x-6sinxcosx-4cos²x+4sin²x-4sin²x-4cos²x=0/cos²x
2tg²x-6tgx-8=0
tg²x-3tgx-4=0
tgx=a
a²-3a-4=0
a1+a2=3 U a1*a2=-4
a1=-1⇒tgx=-1⇒x=π/4+πn,n∈z
a2=4⇒tgx=4⇒x=Arctg4+πk,k∈z