Definition CongruentTriangles (A B C A' B' C' : Point) :=
	Distance A B = Distance A' B' /\
	Distance B C = Distance  B' C' /\
	Distance C A = Distance C' A'.

Lemma CongruentTrianglesA : forall A B C A' B' C' : Point, CongruentTriangles A B C A' B' C' -> A <> B -> A <> C -> Angle B A C = Angle B' A' C'.