proposition: Lemma sams_lea_lta789_suma2__lta456 : forall A B C D E F G H I A' B' C' D' E' F' G' H' I', LeA A' B' C' A B C -> LtA G H I G' H' I' -> SAMS A B C D E F -> SumA A B C D E F G H I -> SumA A' B' C' D' E' F' G' H' I' -> LtA D E F D' E' F'.
proof: Proof. intros A B C D E F G H I A' B' C' D' E' F' G' H' I'. intros. apply (sams_lea_lta789_suma2__lta123 _ _ _ A B C G H I _ _ _ A' B' C' G' H' I'); try (apply suma_sym); auto. apply sams_sym; assumption. Qed.
imports: GeoCoq.Tarski_dev.Ch11_angles