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

Lemma l6_144 : forall A B I A1 A2 B1 B2 C,
on_foot A1 B I A ->
on_line_d A2 A1 B (0-1) ->
on_foot B1 A I B ->
on_line_d B2 B1 A (0-1) ->
inter_ll C A A2 B B2 ->
eq_angle A C I I C B.