proposition: Lemma lea_right_comm : forall A B C D E F, LeA A B C D E F -> LeA A B C F E D.
proof: Proof. intros. apply l11_29_b. apply l11_29_a in H. ex_and H P. exists P. split. assumption. apply conga_right_comm. assumption. Qed.
imports: GeoCoq.Tarski_dev.Ch10_line_reflexivity_2