Things were was executing ok until I added section that I have marked which was supposed to plot the the set union. I was very suspicious of the code that as the offending terms were never defined. Any thoughts on what it should be? And a general question, what is the significance when some identifiers are all in capitol letters, other than the obvious of differentiating it from, a keyword of same name. Is there something more too that?
I know it's a lo of questions however, I've searched through the online docs a my small library of books on Racket. Too either the answers are in there or I've finally slipped over the edge and ready to. be moved to Shady Pines Elder Estate! 
Cheers,
Munroe
The Code:
#lang racket ;set theory 2 PTFW pp 97 thru top of pp 100
(require racket/draw)
(define WIDTH 150)
(define HEIGHT 100)
(define venn (make-bitmap WIDTH HEIGHT))
(define dc (new bitmap-dc% [bitmap venn]))
(send dc scale 1.0 -1.0)
(send dc translate (/ WIDTH 2) (/ HEIGHT -2))
(send dc set-smoothing 'smoothed)
(send dc set-pen "black" 2 'solid)
(define IN-BRUSH (new brush% [color "green"]))
(define OUT-BRUSH (new brush% [ color (make-object color% 220 220 220)]))
(define (rect x y w h b)
(let ([x (- x (/ w 2))]
[y (- y (/ h 2))])
(send dc set-brush b)
(send dc draw-rectangle x y w h)))
(define (circle x y r b)
(let ([x (- x r)]
[y (- y r)])
(send dc set-brush b)
(send dc draw-ellipse x y (* 2 r) (* 2 r))))
(define (universe b) (rect 0 0 (- WIDTH 10) (- HEIGHT 10) b))
(universe OUT-BRUSH)
(circle 0 0 30 IN-BRUSH)
venn
(send dc erase)
(universe IN-BRUSH)
(circle 0 0 30 OUT-BRUSH)
venn
(define (piscis x y r b)
(let* ([y (- y r)]
[2r (* 2 r)]
[y1 (sqrt (- (sqr r) (sqr x)))] ;y-intercept
[π pi]
[ø (asin (/ y1 r))]
[𝜭 (- π ø)]
[path (new dc-path%)])
(send dc set-brush b)
(send path move-to 0 (- y1))
(send path arc (- x r) y 2r 2r 𝜭 (+ π ø))
(send path arc (- (- x) r) y 2r 2r (- ø) ø)
(send dc draw-path path)))
(define SET-BRUSH (new brush% [color (make-object color% 220 255 250)]))
(define(venn-bin b1 b2 b3)
(universe OUT-BRUSH)
;Racket obviously complains that "CIRCLE-OFF is an unbound entity. I ;considering typos such as the offending term should be lower case. But more ;troubling I have no clue what that general form is trying to accomplish?
*****(circle (- CIRCLE-OFF) 0 30 b1)
*****(circle CIRCLE-OFF 0 30 b3)
*****(piscis CIRCLE-OFF 0 30 b2)
(print venn))
(venn-bin IN-BRUSH IN-BRUSH IN-BRUSH)
