# If in $\Delta ABC$ and $\Delta DEF, \large\frac{AB}{DE}=\frac{BC}{FD},\frac{AB}{DE}=\frac{BC}{FD},$ then they will be similar, when
$\begin{array}{1 1} \angle B = \angle E \\ \angle B = \angle D \\ \angle A = \angle D \\ \angle A = \angle F \end{array}$