(* Gabriel Braun March 2013 *)
Require Export GeoCoq.Tarski_dev.Annexes.vectors.
Section Projections.
Context `{T2D:Tarski_2D}.
Context `{TE:@Tarski_euclidean Tn TnEQD}.

Lemma eqv_project_eq_eq :
forall P Q R S P' Q' S' A B X Y,
EqV P Q R S ->
Proj P P' A B X Y ->
Proj Q Q' A B X Y ->
Proj R P' A B X Y ->
Proj S S' A B X Y ->
Q' = S'.