proposition: Lemma equilateral_swap_rot : equilateral A B C -> equilateral C A B.
proof: Proof. intro. apply equilateral_cong in H. unfold equilateral. intuition Cong. Qed.
imports: GeoCoq.Tarski_dev.Ch12_parallel GeoCoq.Tarski_dev.Annexes.perp_bisect