#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))))