proposition: Lemma congaH_commr : forall A B C D E F, ~ColH A B C -> ~ColH D E F -> CongaH A B C D E F -> CongaH A B C F E D.
proof: Proof. intros. apply(th19 E D F B A C ). intro. apply H0; Col. intro. apply H; Col. intro. apply H0; Col. apply congaH_sym; auto. apply conga_comm; auto. Qed.
imports: Setoid Coq.Classes.Morphisms Coq.Classes.Morphisms_Prop GeoCoq.Axioms.gupta_inspired_variant_axioms GeoCoq.Meta_theory.Models.gupta_inspired_to_tarski GeoCoq.Tactics.Coinc.tactics_axioms GeoCoq.Tactics.Coinc.ColR GeoCoq.Meta_theory.Dimension_axioms.upper_dim_3 GeoCoq.Meta_theory.Parallel_postulates.parallel_postulates GeoCoq.Axioms.hilbert_axioms