Require Export GeoCoq.Elements.OriginalProofs.lemma_samesideflip.
Require Export GeoCoq.Elements.OriginalProofs.proposition_39A.
Section Euclid.
Context `{Ax:area}.

(* Specifications: *)
Lemma proposition_39 :
forall A B C D,
Triangle A B C -> Triangle D B C -> OS A D B C -> ET A B C D B C -> neq A D ->
Par A D B C.