proposition: Lemma g2_2 : forall A B C D, CongG A B C D -> CongG C D A B.
proof: Proof. intros A B C D HCong. apply cong_inner_transitivityG with C D; auto; apply g2_1. Qed.
imports: GeoCoq.Axioms.tarski_axioms GeoCoq.Axioms.gupta_inspired_variant_axioms GeoCoq.Tarski_dev.Ch05_bet_le