In triangles $ABC$ and $PQR$,$\angle A = \angle Q$ and $\angle B = \angle R$. Which side of $\triangle PQR$ should be equal to side $BC$ of $\triangle ABC$ so that the two triangles are congruent? Give reason for your answer.

(N/A) In triangles $ABC$ and $PQR$,we are given:
$\angle A = \angle Q$ and $\angle B = \angle R$.
For the two triangles to be congruent by the $AAS$ (Angle-Angle-Side) congruence rule,the side corresponding to $BC$ in $\triangle ABC$ must be equal to the side corresponding to $RP$ in $\triangle PQR$.
Therefore,$BC = RP$.
This ensures that the two triangles are congruent by the $AAS$ congruence criterion.