Proof with Tarski.
intros.
unfold le in H.
DecompExAnd H Y.
assert (exists C' : Point, Cong_3 C Y D A B C').
eapply l4_14;unfold Col;sTarski.
DecompEx H X.
exists X.
unfold Cong_3 in H0;intuition;sTarski.
eapply l4_6.
apply H1.
unfold Cong_3;intuition;sTarski.
Qed.

(* Specifications: *)
Lemma l5_5_2 : forall A B C D,
(exists x, Bet A B x /\ Cong A x C D) -> le A B C D.