proposition: Lemma prop_5_1 : forall A B C, A <> B -> B <> C -> Cong A B A C -> CongA A B C A C B.
proof: Proof. intros. apply l11_44_1_a; auto. Qed.
imports: GeoCoq.Meta_theory.Continuity.elementary_continuity_props GeoCoq.Tarski_dev.Ch16_coordinates_with_functions