(** If the angles ACB and ADB are supplementary and inscribed in the same circle, then C and D lie on opposite sides of AB. *)

Lemma cop2_onc4_suppa__ts : forall O P A B C D, ~ Col A B O ->
OnCircle A O P -> OnCircle B O P -> OnCircle C O P -> OnCircle D O P ->
Coplanar A B O C -> Coplanar A B O D -> SuppA A C B A D B ->
TS A B C D.