Упростить (/- дробь) tg2a*tga/tg2a-tga

[latex] \frac{tg2a\cdot tga}{tg2a-tga} = \frac{sin2a\cdot sina}{cos2a\cdot cosa\cdot (\frac{sin2a}{cos2a}-\frac{sina}{cosa})}=\\\\=\frac{sin2a\cdot sina\cdot cos2a\cdot cosa}{cos2a\cdot cosa\cdot (sin2a\cdot cosa-cos2a\cdot cosa)} =\frac{sin2a\cdot sina}{sin(2a-a)} = \frac{sin2a\cdot sina}{sina} =sin2a[/latex]