proposition: Lemma col_bet2_cong2 : forall A B C D, Col A B D -> Bet A C B -> Cong A B C D -> Bet C A D -> Cong D A B C.
proof: Proof. intros. apply (l4_3 D A C B C A); Between; Cong. Qed.
imports: GeoCoq.Tarski_dev.Ch06_out_lines GeoCoq.Tarski_dev.Tactics.ColR