If three sides of a triangle are respectively equal to the corresponding three sides of another triangle, then the triangle are congruent.

General enunciation: If three sides of a triangle are respectively equal to the corresponding three sides of another triangle, then the triangle are congruent.   Particular enunciation:  Let, in ∆ABC and ∆DEF, AB = PQ, AC = PR and BC = QR. It is required to prove that, ∆ABC ≌ ∆PQR. Proof: Let BC and ...