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

Lemma proposition_28A :
forall A B C D E G H,
BetS A G B -> BetS C H D -> BetS E G H -> CongA E G B G H D -> OS B D G H ->
Par A B C D.