Require Export GeoCoq.Elements.OriginalProofs.lemma_lessthanbetween.
Require Export GeoCoq.Elements.OriginalProofs.lemma_lessthanadditive.
Section Euclid.
Context `{Ax:euclidean_neutral_ruler_compass}.

Lemma lemma_21helper :
forall A B C E,
TG B A A E B E -> BetS A E C ->
TT B A A C B E E C.