another yucky geometry question

[Chipp Walters]

It does appear from your illustration, you can calculate the major and 
minor access vectors.

You could also consider doing an axonometric drawing tool, that way you 
only ever need know 3 different ellipses (top,left,right).

Or, you could calculate it using trig and the designer's trick where you 
draw the box, bisect it horizontally, vertically and diagonally (both 
ways), then compute a polygon based upon the tangents to the horizontal 
and vertical bisectors, and 2/3 the diagonal bisectors. A bit of 
interpolation and you could probably estimate a decent ellipse.

-Chipp