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

Lemma eqv_sum :
forall A B C A' B' C',
EqV A B A' B' ->
EqV B C B' C' ->
EqV A C A' C'.