Feb. 4, 2011

pp. 258-259: Formatting errors that caused overprinting. It should read:

Then we need to add those two squares:

(define (distance-to-top-left the-point) ; the-point a posn ; (posn-x the-point) a number (x) ; (posn-y the-point) a number (y) ; (* (posn-x the-point) (posn-x the-point)) a number (x^{2}) ; (* (posn-y the-point) (posn-y the-point)) a number (y^{2}) ; (+ (* (posn-x the-point) (posn-x the-point)) ; (* (posn-y the-point) (posn-y the-point))) a number (x^{2}+y^{2}) ...)

and finally square-root that, using `sqrt`

:

(define (distance-to-top-left the-point) ; the-point a posn ; (posn-x the-point) a number (x) ; (posn-y the-point) a number (y) ; (* (posn-x the-point) (posn-x the-point)) a number (x^{2}) ; (* (posn-y the-point) (posn-y the-point)) a number (y^{2}) ; (+ (* (posn-x the-point) (posn-x the-point)) ; (* (posn-y the-point) (posn-y the-point))) a number (x^{2}+y^{2}) (sqrt (+ (* (posn-x the-point) (posn-x the-point)) (* (posn-y the-point) (posn-y the-point)))) )