proposition: Lemma conga3_defect__defect : forall A B C D E F A' B' C', Defect A B C D E F -> CongA A B C A' B' C' -> CongA B C A B' C' A' -> CongA C A B C' A' B' -> Defect A' B' C' D E F.
proof: Proof. intros A B C D E F A' B' C' HDef HCongaB HCongaC HCongaA. destruct HDef as [G [H [I [HTri HSuppa]]]]. exists G, H, I. split; trivial. apply (conga3_trisuma__trisuma A B C); trivial. Qed.
imports: GeoCoq.Tarski_dev.Annexes.saccheri