In the above case, we first note that
∠PQR=60∘ (Angle sum property).
Now, AB = PQ, BC = QR and
∠PQR=∠ABC=60∘. Thus, the triangles are congruent by SAS criterion.
In this case,
∠ABC=∠PQR, BC = QR and
∠ACB=∠PRQ.
Thus, the triangles are congruent by ASA criterion.
In this case, we note that
∠ACB=∠PQR=60∘ (Angle Sum Property).
We also note that when all angles of a triangle are
60∘, then the triangle is equilateral.
Thus, we have AB = BC = AC = PQ = QR = PR = 6 cm and by SSS criterion, the triangles are congruent.