(load "2_2.sch")

(define (make-rect-corners top-left bottom-right)
  (let ((top-right 
	  (make-point (x-point bottom-right) (y-point top-left)))
	(bottom-left
	  (make-point (x-point top-left) (y-point bottom-right))))
       (list top-left top-right bottom-right bottom-left)))

(define (make-rect-size bottom-left width height)
  (let ((top-left
	  (make-point (x-point bottom-left) 
		      (+ height (y-point bottom-left))))
	(top-right
	  (make-point (+ width (x-point bottom-left))
		      (+ height (y-point bottom-left))))
	(bottom-right
	  (make-point (+ width (x-point bottom-left))
		      (y-point bottom-left))))
	(list top-left top-right bottom-right bottom-left)))


(define (rect-top-left r) (car r))
(define (rect-top-right r) (cadr r))
(define (rect-bottom-right r) (caddr r))
(define (rect-bottom-left r) (cadddr r))

(define (perimeter r)
  (let ((tl (rect-top-left r))
	(br (rect-bottom-right r)))
       (+
       	(* 2 (abs (- (x-point br) (x-point tl))))
       	(* 2 (abs (- (y-point br) (y-point tl)))))))

(define (area r)
  (let ((tl (rect-top-left r))
	(br (rect-bottom-right r)))
       (*
	(abs (- (x-point tl) (x-point br)))
	(abs (- (y-point tl) (y-point br))))))