Require Export GeoCoq.Elements.OriginalProofs.lemma_NCdistinct.
Require Export GeoCoq.Elements.OriginalProofs.lemma_NCorder.
Require Export GeoCoq.Elements.OriginalProofs.lemma_NChelper.
Require Export GeoCoq.Elements.OriginalProofs.lemma_equalanglesreflexive.
Section Euclid.
Context `{Ax:euclidean_neutral_ruler_compass}.

Lemma proposition_13 :
forall A B C D,
BetS D B C -> nCol A B C ->
RT C B A A B D.