Section T15.
Context `{T2D:Tarski_2D}.
Context `{TE:@Tarski_euclidean Tn TnEQD}.
(** Lemma 15.2 *)
(** Cong corresponds to length equality.*)
(** Le corresponds to length inequality.*)
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Lemma cong2_lea__le :   forall A B C D E F : Tpoint,
Cong A B D E -> Cong A C D F -> LeA F D E C A B -> Le E F B C.