proposition: Lemma rect_permut : forall A B C D, Rectangle A B C D -> Rectangle B C D A.
proof: Proof. intros. unfold Rectangle in *. spliter. split. apply plg_to_parallelogram in H. apply plg_permut in H. apply parallelogram_to_plg in H. assumption. Cong. Qed.
imports: GeoCoq.Tarski_dev.Ch12_parallel_inter_dec GeoCoq.Tarski_dev.Annexes.Tagged_predicates