Dear Rudolph,

Glad you enjoyed the puzzle or, at least,
the solution...

> Brilliant!

You add...

> I never realized that the distance from
> the focus to the end of the minor axis
> equals the half major axis...

Have you never tried drawing an ellipse
with a Length of String and Two Pins?

This is illustrated all over the web,
for example here:

  http://bogan.ca/orbits/kepler.html

This is a very bad way of drawing an
ellipse but the theory is sound!

In this illustration, the two ends of
the string are each tied to one of
the two pins.  The pins are at the
two foci.

Now imagine the pencil point at one
end of the major axis.  It is then
obvious that the total length of
the string equals the major axis.

Then imagine the pencil point at
one end of the minor axis.  It is
then obvious that the total length
of the string equals twice the
distance from a focus to one end
of the minor axis.

If you try this in real life you
will find you draw a potato shape!

[Well that's what happens if I do
it but there is nothing wrong with
the idea!]

Frank

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