Require Export GeoCoq.Elements.OriginalProofs.lemma_equalanglesflip.
Require Export GeoCoq.Elements.OriginalProofs.proposition_16.
Require Export GeoCoq.Elements.OriginalProofs.lemma_angletrichotomy.
Require Export GeoCoq.Elements.OriginalProofs.lemma_collinearbetween.
Section Euclid.
Context `{Ax:euclidean_neutral_ruler_compass}.

(* Specifications: *)
Lemma proposition_27 :
forall A B C D E F,
BetS A E B -> BetS C F D -> CongA A E F E F D -> TS A E F D ->
Par A B C D.