ĐK: x#kpi
[TEX]3.\frac{cos^2x}{sin^2x}+\frac{3.(\frac{cosx}{sinx}+1)}{sinx}-4\sqrt{2}.(\frac{\sqrt{2}}{2}.cosx+\frac{\sqrt{2}}{2}.sinx)=1[/TEX]
\Leftrightarrow [TEX]3cos^2x+3cosx+3sinx-4.sin^2x.cosx-4sin^3x-sin^2x=0[/TEX]
\Leftrightarrow [TEX](3cos^2x-sin^2x)+(3cosx-4sin^2xcosx)+(3sinx-4sin^3x)=0[/TEX]
\Leftrightarrow [TEX]4cos^2x-1+cosx(4cos^2x-1)+sinx(4cos^2x-1)=0[/TEX]
Đến đây thì dễ rồi