; Rectangle usage procedures
(define (rectangle-square r)
  (* (rectangle-width r) (rectangle-height r)))
(define (rectangle-perimeter r)
  (+ (* (rectangle-width r) 2) (* (rectangle-height r) 2)))

; Rectangles
(define (make-rectangle start-p width height)
  (cons start-p (cons width height)))
(define (rectangle-point r)
  (car r))
(define (rectangle-width r)
  (car (cdr r)))
(define (rectangle-height r)
  (cdr (cdr r)))