Section Quadrilateral_inter_dec_1.
Context `{TE:Tarski_euclidean}.

Lemma par_cong_mid :
forall A B A' B',
Par A B A' B' ->
Cong A B A' B' ->
exists M,  Midpoint M A A' /\ Midpoint M B B' \/
Midpoint M A B' /\ Midpoint M B A'.