đây rồi...$Tử Số=2sin2x+2sinx.cosx$
$Mẫu Số=2sin2x+2sin2x.sinx$
$\Rightarrow BT=\frac{cosx+1}{sinx+1}=\frac{2cos^{2}\frac{x}{2}}{(sin\frac{x}{2}+cos\frac{x}{2})^{2}*}=\frac{2}{(1+tan\frac{x}{2})^{2}}$
*$sinx+1=2sin\frac{x}{2}cos\frac{x}{2}+sin^{2}\frac{x}{2}+cos^{2}\frac{x}{2}$