Section T11_2.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** This is exterior angle theorem *)

Lemma conga_preserves_lta : forall A B C D E F A' B' C' D' E' F',
CongA A B C A' B' C' ->
CongA D E F D' E' F' ->
LtA A B C D E F ->
LtA A' B' C' D' E' F'.