#lang racket
(require (planet wcy/mpost-wrapper))
(provide main)
(define (arc O A B rou)
  (let ((alpha (op-angle (op- A O)))
        (beta  (op-angle (op- B O))))
    (path (op+ O (polar rou alpha)) (dir-spec (dir (op+ alpha 90))) ".."
          (op+ O (polar rou beta )) (dir-spec (dir (op+ beta  90))))))
(define (draw-angle A B C n)
  (let ((rou '4.5mm))
    (if (> n 0)
        (begin
          (draw (arc A B C (op+ rou (op* n '0.5mm))))
          (draw-angle  A B C (- n 1)))
        (void))))
(define (main)
  (let ((A (point 0 0))
        (B (point '3cm 0))
        (C (point '1cm '2cm)))
    (draw (op-- A B C 'cycle))
    (draw-angle A B C 1)
    (draw-angle B C A 2)
    (draw-angle C A B 3)))