(** * Proposition 30 Straight lines parallel to the same straight line are also parallel to one another. *)
(** # <div style="width:748px;height:397px;display:block" id="applet_container30"></div> # **)

(* Specifications: *)
Lemma prop_30 : forall A B C D E F, Par A B C D -> Par C D E F ->
Par A B E F.