Proof with Tarski.
intros.
unfold Col in H;intuition.
assert (exists C', Bet A' B' C' /\ Cong B' C' B C)...
DecompExAnd H C'.
assert (Cong A C A' C').
eapply l2_11;esTarski.
exists C'...
unfold Cong_3;intuition...
Focus 2.
assert (exists C', Bet B' A' C' /\ Cong A' C' A C)...
DecompExAnd H1 C'.
exists C'...
unfold Cong_3;intuition...
eapply ( l2_11 B A C B' A' C');esTarski.
assert (exists B'0 : Point, Bet B' B'0 A' /\ Cong_3 B C A B' B'0 A').
eapply l4_5;esTarski.
DecompExAnd H1 C'.
exists C'...
unfold Cong_3 in *;intuition...
Qed.
(** Five segments configuration. *)
Definition FSC := fun A B C D A' B' C' D' =>
Col A B C /\ Cong_3 A B C A' B' C' /\ Cong A D A' D' /\ Cong B D B' D'.

Lemma l4_16 :  forall A B C D A' B' C' D',
FSC A B C D A' B' C' D' -> A<>B -> Cong C D C' D'.