Require Export GeoCoq.Elements.OriginalProofs.lemma_ABCequalsCBA.
Require Export GeoCoq.Elements.OriginalProofs.lemma_equalanglestransitive.
Section Euclid.
Context `{Ax:euclidean_neutral_ruler_compass}.

Lemma lemma_equalanglesflip :
forall A B C D E F,
CongA A B C D E F ->
CongA C B A F E D.