On Jul 20, 2010, at 1:07 AM, Mathew Kurian <bluejamesb...@gmail.com> wrote:

> in this example given by Paul Ojanen ...
> 
> The triangle is not being consistent by keeping its center point on the 
> center of BACKGROUND.

Yes it is.  The problem is that what you think of as the "center" of an 
equilateral triangle (where the three angle bisectors meet) isn't quite the 
same as what 2htdp/image considers the "center" (the center of the bounding 
rectangle).  However, if you figure out (by trigonometry) where the former 
"center" is, and overlay an invisible circle centered at that point, then when 
you rotate the whole complex, that point will appear unmoving.

Steve Bloch

> Hopefully, this makes sense.

Ditto :-)


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