(***************************************************************************)
(* Formalization of the Chou, Gao and Zhang's decision procedure.          *)
(* Julien Narboux (Julien@narboux.fr)                                      *)
(* LIX/INRIA FUTURS 2004-2006                                              *)
(* University of Strasbourg 2008-2009                                      *)
(***************************************************************************)
Require Export euclidean_constructions.
Require Export area_elimination_lemmas.
Require Export ratios_elimination_lemmas.

(* lemme 3_2 chou *)
Lemma l_24_a : forall A B P D,
Col A D B -> perp A B P D ->
A<>B -> B<>D ->
A**D / D**B = Py P A B / Py P B A.