(***************************************************************************)
(* Formalization of the Chou, Gao and Zhang's decision procedure.          *)
(* Julien Narboux (Julien@narboux.fr)                                      *)
(* LIX/INRIA FUTURS 2004-2006                                              *)
(* University of Strasbourg 2008                                           *)
(***************************************************************************)
Require Export area_method.

Lemma l6_88 : forall A B C O A1 B1 C1,
is_circumcenter O A B C ->
is_midpoint A1 B C ->
is_midpoint B1 A C ->
is_midpoint C1 A B ->
perp O A1 B1 C1.