(** Euclid Book III Prop 23: On the same straight line there cannot be constructed two similar and unequal segments of circles on the same side. *)

Lemma conga_cop_onc3_os__onc : forall A B C D O P,
OnCircle A O P -> OnCircle B O P -> OnCircle C O P ->
Coplanar A B C O -> OS A B C D -> CongA A C B A D B ->
OnCircle D O P.