Require Export GeoCoq.Elements.OriginalProofs.lemma_supplementsymmetric.
Require Export GeoCoq.Elements.OriginalProofs.lemma_oppositesidesymmetric.
Require Export GeoCoq.Elements.OriginalProofs.proposition_27.
Section Euclid.
Context `{Ax:euclidean_neutral_ruler_compass}.

(* Specifications: *)
Lemma proposition_28B :
forall A B C D G H,
BetS A G B -> BetS C H D -> RT B G H G H D -> OS B D G H ->
Par A B C D.