(* Gabriel Braun November 2012 *)
Require Export GeoCoq.Tarski_dev.Ch12_parallel.
Section Quadrilateral.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma midpoint_cong_uniqueness :
forall A B C D M,
Col A B C ->
Midpoint M A B /\ Midpoint M C D ->
Cong A B C D ->
A = C /\ B = D \/ A = D /\ B = C.