proposition: Lemma conga_preserves_lta : forall A B C D E F A' B' C' D' E' F', CongA A B C A' B' C' -> CongA D E F D' E' F' -> LtA A B C D E F -> LtA A' B' C' D' E' F'.
proof: Proof. intros. unfold LtA in *. spliter. split. eapply l11_30. apply H1. assumption. assumption. intro. apply H2. eapply conga_trans. apply H. eapply conga_trans. apply H3. apply conga_sym. assumption. Qed.
imports: GeoCoq.Tarski_dev.Ch10_line_reflexivity_2