vect.scm

(define (make-vect x y)
  (cons x y))
(define (xcor-vect v)
  (car v))
(define (ycor-vect v)
  (cdr v))
(define (add-vect v1 v2)
  (make-vect (+ (xcor-vect v1) (xcor-vect v2))
	     (+ (ycor-vect v1) (ycor-vect v2))))
(define (sub-vect v1 v2)
  (make-vect (- (xcor-vect v1) (xcor-vect v2))
	     (- (ycor-vect v1) (ycor-vect v2))))
(define (scale-vect s v)
  (make-vect (* s (xcor-vect v))
	     (* s (ycor-vect v))))
(define (make-frame origin edge1 edge2)
  (list origin edge1 edge2))
(define (origin-frame f)
  (car f))
(define (edge1-frame f)
  (cadr f))
(define (edge2-frame f)
  (caddr f))
(define (make-segment start end)
  (list start end))
(define (start-segment s)
  (car s))
(define (end-segment s)
  (cadr s))