Require Export GeoCoq.Tarski_dev.Ch14_order.
Section T15.
Context `{T2D:Tarski_2D}.
Context `{TE:@Tarski_euclidean Tn TnEQD}.
(** Lemma 15.2 *)
(** Cong corresponds to length equality.*)
(** Le corresponds to length inequality.*)

Lemma project_preserves_out : forall A B C A' B' C' P Q X Y,
Out A B C -> ~Par A B X Y ->
Proj A A' P Q X Y -> Proj B B' P Q X Y -> Proj C C' P Q X Y ->
Out A' B' C'.