Require Export GeoCoq.Elements.OriginalProofs.proposition_16.
Require Export GeoCoq.Elements.OriginalProofs.proposition_05.
Require Export GeoCoq.Elements.OriginalProofs.lemma_angleordertransitive.
Section Euclid.
Context `{Ax:euclidean_neutral_ruler_compass}.

Lemma proposition_18 :
forall A B C,
Triangle A B C -> Lt A B A C ->
LtA B C A A B C.