1 (define (add-vect u v)
2   (make-vect
3    (+ (xcor-vect u) (xcor-vect v))
4    (+ (ycor-vect u) (ycor-vect v))))
5 (define (sub-vect u v)
6   (make-vect
7    (- (xcor-vect u) (xcor-vect v))
8    (- (ycor-vect u) (ycor-vect v))))
9 (define (scale-vect s v)
10   (make-vect (* s (xcor-vect v))
11 	     (* s (ycor-vect v))))
12 
13