(** another statement for nine point circle theorem *)

Theorem th6_259 :
forall A B C D E F G H R L : Point,
on_parallel_d E A B D 1 ->
on_parallel_d G A C F 1 ->
inter_ll H D E F G ->
inter_ll R B C H A ->
on_parallel_d L B H A 1 ->
S F A B <> 0 ->
S A C F + S B A D = S C B L.