(***************************************************************************)
(* 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_196 : forall A B C E F G O,
is_circumcenter O A B C ->
on_foot E O B C ->
on_foot F O A C ->
on_foot G O A B ->
S A B C= 2*2 * S E F G.