examples/ex-70.rkt
#lang racket
(require (planet wcy/mpost-wrapper))
(provide main)
(define (main)
  (let* ((A (point 0 0))
         (B (point '2cm '3cm))
         (C (point '1cm 0))
         (D (point '-1cm '2cm))
         (M (unknown-point)))
    (eqn= M  (mediation (whatever)  A B)
          (mediation (whatever) C D))
    (draw (op-- A B))
    (draw (op-- C D))
    (draw M #:withpen (scale '4bp 'pencircle))))