With reference to my earlier post:

I would like to add an outer circle to the whole drawing. This outer circle is a fixed one of radius 40. Something like this is helpful:

Graphics[Circle[{0, 0}, 40]]


But I do not know exactly where to put it in my code so that it remain a fixed circle in the background.

Thanks a lot...

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Does adding PlotRange->All help? (I cannot test at the moment). I think the problem is that show takes the options (including the plot range) is taken from the first argument, and that's too small to see the circle. Another thing you could do is to put the large circle first (because AFAICS it doesn't intersect with the RegionPlot anyway). –  celtschk Mar 24 '12 at 16:42
If you posted actual working code showing the problem, the chances would be better that anyone understands what your problem is. –  celtschk Mar 24 '12 at 17:29

You need a large enough PlotRange, or

circ11 = Show[circ, Graphics[Circle[{0, 0}, 40]], PlotRange -> All]


Edit: are you referring to Heike's code? If so, you could simply replace her plot[t] function by something like:

plot[t_] :=
Show[Graphics[{Circle[{0, 0}, 40],
Translate[Rotate[{circ[[1]], Point[{0, 0}]}, om2 t], centre[t]]}],
If[Abs[t] <= \$MachineEpsilon, {},
ParametricPlot[centre[s], {s, 0, t}, PlotStyle -> {Black}]],