Here, from the figure we see that,
Line EI is parallel to HG.
And EH and GI act as the transversal lines for the given parallel pair.
So, we get
[tex]\begin{gathered} \angle G=\angle I\text{ (alternate angles)} \\ \angle E=\angle H\text{ (alternate angles)} \\ \angle EFI=\angle GFH(vertically\text{ opposite angles)} \end{gathered}[/tex][tex]\text{Also in }\Delta EIF\text{ side }FI\text{ is given equal to side }FG\text{ in }\Delta FGH[/tex]Therefore, we have two angles and one side equal in two triangles.
Henceproved that , they are congruent with the ASA (Angle Side Angle)rule.