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

Lemma CongruentStrictTrianglesASABC : forall A B C A' B' C' : Point,
Distance B C = Distance B' C' ->
Angle A B C = Angle A' B' C' ->
Angle B C A = Angle B'  C' A' ->
~Collinear A B C ->
CongruentStrictTriangles A B C A' B' C'.