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(* Formalization of the Chou, Gao and Zhang's decision procedure.          *)
(* Julien Narboux (Julien@narboux.fr)                                      *)
(* LIX/INRIA FUTURS 2004-2006                                              *)
(* University of Strasbourg 2008                                           *)
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(** nine point circle *)
(** another statement for nine point circle theorem *)

Theorem th6_259 :
forall A B C D E F G H R L : Point,
on_parallel_d E A B D 1 ->
on_parallel_d G A C F 1 ->
inter_ll H D E F G ->
inter_ll R B C H A ->
on_parallel_d L B H A 1 ->
S F A B <> 0 ->
S A C F + S B A D = S C B L.