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Topic: Hyperbolas in Nature
Replies: 29   Last Post: Mar 24, 2010 6:05 AM

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John Conway

Posts: 2,238
Registered: 12/3/04
Re: Hyperbolas in nature
Posted: May 12, 1996 2:40 PM
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On 10 May 1996, C. Kenneth Fan wrote:

> I think I've got another one:
> Hold a large hoola hoop around yourself, look straight forward, and close one of
> your eyes. (Don't look down directly at the hoop, just view it vertically
> askance.) Then, chances are you'll have a hyperbola across your field of
> vision...If you've got just incredibly over-exagerated posture, you might
> catch a parabola, or even an ellipse, but for me, I'd end up cheating by
> tilting my head down or I'd break my back to see the ellipse this way.
> Ken

This one supposes that one's visual field has been identified with
a plane, which admittedly is the usual assumption, but usually it's
really being made only of a small portion of the visual field, and here
it's a large one, which would more naturally be identified with a
hemisphere (or, at least, SOME portion of a sphere).

John Conwaqy

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