Require Export GeoCoq.Elements.OriginalProofs.lemma_ABCequalsCBA.
Require Export GeoCoq.Elements.OriginalProofs.lemma_supplements.
Require Export GeoCoq.Elements.OriginalProofs.lemma_equalanglestransitive.
Section Euclid.
Context `{Ax:euclidean_neutral_ruler_compass}.

Lemma proposition_15 :
forall A B C D E,
BetS A E B -> BetS C E D -> nCol A E C ->
CongA A E C D E B /\ CongA C E B A E D.