Require Export GeoCoq.Elements.OriginalProofs.lemma_betweennotequal.
Require Export GeoCoq.Elements.OriginalProofs.lemma_localextension.
Require Export GeoCoq.Elements.OriginalProofs.lemma_extensionunique.
Section Euclid.
Context `{Ax:euclidean_neutral_ruler_compass}.

Lemma lemma_3_7a :
forall A B C D,
BetS A B C -> BetS B C D ->
BetS A C D.