2.03.scm

(define (print-point p)
  (newline)
  (display "(")
  (display (x-point p))
  (display ",")
  (display (y-point p))
  (display ")"))

(define (make-point x y) (cons x y))
(define (x-point p) (car p))
(define (y-point p) (cdr p))

(define (make-segment p1 p2) (cons p1 p2))
(define (start-segment s) (car s))
(define (end-segment s) (cdr s))

(define (segment-length s)
  (define (square n)
    (* n n))
  (sqrt (+ (square (abs (- (x-point (start-segment s))
                           (x-point (end-segment s)))))
           (square (abs (- (y-point (start-segment s))
                           (y-point (end-segment s))))))))

(define (make-rectangle s1 s2) (cons s1 s2))
(define (rect-width r) (segment-length (car r)))
(define (rect-height r) (segment-length (cdr r)))

(define (rect-perimeter r)
  (* 2 (+ (rect-width r) (rect-height r))))

(define (rect-area r)
  (* (rect-width r) (rect-height r)))

(let* ((p1 (make-point 0 0))
       (p2 (make-point 2 0))
       (p3 (make-point 0 2))
       (s1 (make-segment p1 p2))
       (s2 (make-segment p1 p3))
       (r (make-rectangle s1 s2)))
  (rect-perimeter r))