#lang racket
(require (planet wcy/mpost-wrapper))
(provide main)
(define (main)
  (let ((A (unknown-point))
        (B (unknown-point))
        (C (unknown-point))
        (D (unknown-point)))
    (eqn= (xpart A) (ypart A) (ypart B) (xpart C) 0)
    (eqn= (xpart B) (ypart C) (xpart D) (ypart D) '2cm)
    (draw (op-- A B C D 'cycle)
          #:withpen (scale '2bp 'pencircle))))