proposition: Lemma cong_conga3_cong3 : forall A B C A' B' C', ~ Col A B C -> Cong A B A' B' -> CongA_3 A B C A' B' C' -> Cong_3 A B C A' B' C'.
proof: Proof. intros. unfold CongA_3 in H1. spliter. assert(Cong A C A' C' /\ Cong B C B' C' /\ CongA C A B C' A' B'). apply( l11_50_2 A B C A' B' C' H); auto. spliter. repeat split; auto. Qed.
imports: GeoCoq.Tarski_dev.Annexes.vectors