1-5-3.rkt

;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname 1-5-3) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f () #f)))
; 1-5-2 stuff
(define p (make-posn 31 26))
;(posn-x p)
;(posn-x (make-posn 31 26))


; computes the distance of ap to the origin 
(define (distance-to-0 ap)
  (sqrt (+ (sqr (posn-x ap)) (sqr (posn-y ap)))))

(check-expect (distance-to-0 (make-posn 0 5)) 5)
(check-expect (distance-to-0 (make-posn 7 0)) 7)
(check-expect (distance-to-0 (make-posn 3 4)) 5)
(check-expect (distance-to-0 (make-posn 8 6)) 10)
(check-expect (distance-to-0 (make-posn 5 12)) 13)

(distance-to-0 (make-posn 3 4))

(distance-to-0 (make-posn 6 (* 2 4)))

(+ (distance-to-0 (make-posn 12 5)) 10)


(define (manhattan-distance ap)
  (+ (abs (posn-x ap)) (abs (posn-y ap))))

(check-expect (manhattan-distance (make-posn 0 5)) 5)
(check-expect (manhattan-distance (make-posn -7 0)) 7)
(check-expect (manhattan-distance (make-posn 3 4)) 7)
(check-expect (manhattan-distance (make-posn 8 -6)) 14)