∵AM is the median of △ABC
⇒BM=CM=12BC
∵PN is the median of △PQR
QN=RN=12QR
Since, BC=QR
12BC=12QR
BM=QN
⇒AB=PQ;AM=PN;BM=QN
∴△ABM≅△PQN [by SSS Criteria]
∴∠B=∠Q [CPCT]
In △ABC and △PQR,
AB=PQ [given]
∠B=∠Q and BC=QR
∴△ABC≅△PQR ..... [SAS Congruence Rule][henceproved]