# If in two triangles $ABC$ and $DEF,\large\frac{AB}{DE}=\frac{BC}{FE}=\frac{CA}{FD},$ then
$\begin{array}{1 1} FDE \approx \Delta CAB \\ BCA \approx \Delta FDE \\ \Delta FDE \approx \Delta ABC \\ \Delta CBA \approx \Delta FDE \end{array}$