Answer
$\overline{AB}$
Work Step by Step
In congruent polygons, vertices are named in the exact order of their matching angles and sides.
If $ABCD$ is congruent to $EFGH$, then vertex $A$ corresponds to vertex $E$, vertex $B$ corresponds to vertex $F$, vertex $C$ corresponds to vertex $G$, and vertex $D$ corresponds to vertex $H$.
Therefore, $\overline{EF}$ is congruent to $\overline{AB}$.
