Require Export GeoCoq.Elements.OriginalProofs.lemma_ray1.
Require Export GeoCoq.Elements.OriginalProofs.lemma_interior5.
Section Euclid.
Context `{Ax:euclidean_neutral_ruler_compass}.

Lemma lemma_8_3 :
forall A B C D,
Per A B C -> Out B C D ->
Per A B D.