Answer:
To prove
∠ABC = ∠PQR
Using euclidean distance, Length of each side can be found as
As can be seen
AB ≅ PQ
BC ≅ QR
CA ≅ RP
As all the sides of ΔABC are equal and congruent to ΔPQR, this Proves that measure of all angles inside both triangles must be equal.