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