Lemma bet_betCood : forall O E S U1 U2 A AX AY B BX BY C CX CY, Cd O E S U1 U2 A AX AY -> Cd O E S U1 U2 B BX BY -> Cd O E S U1 U2 C CX CY -> Bet A B C -> Bet AX BX CX /\ Bet AY BY CY.