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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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(** Area elimination *)
(** on_line *)
(** on_line_d *)
(* inter_ll *)

Lemma test_area_on_inter_line_parallel_1 : forall I A B C D E X Y,
on_inter_line_parallel I A B C D E -> False ->
S X Y I = (S4 D B E A * S X Y C - S4 D C E A * S X Y B) / S4 D B E C .