4cos^2x+sinxcosx+3sin^2-3=0

4cos²x + sinx * cosx + 3sin²x - 3 = 0  4cos²x + sinx * cosx + 3sin²x - 3(sin²x + cos²x) = 0 4cos²x + sinx * cosx + 3sin²x - 3sin²x - 3cos²x = 0 cos²x + sinx * cosx = 0  cosx * (cosx + sinx)=0 cosx = 0    x=π/2 + πn,n ∈ Z cosx + sinx = 0 |:cosx  1+ tgx = 0  tgx = -1   x=-π/4 + πn,n ∈