(define CENTER (make-posn 200 200))
(define RADIUS 200)

(define (circle-pt factor)
  (local
    (
     (define ang (degrees->radians (fraction->degrees factor)))
     (define x (posn-x CENTER))
     (define y (posn-y CENTER))
     (define new-x (- x (* RADIUS (cos ang))))
     (define new-y (- y (* RADIUS (sin ang))))
     )
    (make-posn
     new-x
     new-y
     )
    )
  )

(define (fraction->degrees fraction)
  (* 360 fraction)
  )

(define (degrees->radians deg)
  (/(* deg pi) 180)
  )