Definition CongruentStrictTriangles (A B C A' B' C' : Point) :=
	CongruentTriangles A B C A' B' C' /\
	~Collinear A B C.

Lemma CongruentStrictTrianglesAB : forall A B C A' B' C' : Point, CongruentStrictTriangles A B C A' B' C' -> Distance A B = Distance A' B'.