[TheForge] Ellipse generator?

[Chris Kilpatrick]

Andy,
At the longest point the string forms two straight lines, at the shortest point the string forms an equilateral triangle, such that (the distance from the pin to the narrowest point) squared - (1/2 the distance between the pins)squared equals (half the width at the narrowest point) squared.

So we need a triangle where (pin to narrowest point) squared - (1/2 distance between pins) squared = 9 (3 squared, or half the narrowest distance squared) But where distance between pins + pin to narrowest point + pin to narrowest point = {(12- distance between pins)/2 + distance between pins} x 2.

The last two statements describe the length of the string

Hope this helps,

Chris

----- Original Message -----
From: "Andrew Vida" <osan at netlabs.net>
To: "Sponsored by ABANA" <theforge at mailman.qth.net>
Subject: Re: [TheForge] Ellipse generator?
Date: Fri, 17 Dec 2004 10:03:42 -0500

> 
> 
> 
> Chris Kilpatrick wrote:
> > Approximately 10 3/8" apart, your string loop should be 11 3/16"  when tied.
> 
> 	How did you arive at this?  I measure it as 9".  The major axis == 
> 12" and the minor == 6".  A 6" interval, centered on the 12" major 
> axis leaves 3" per side to the ends of the major.  Distance from 
> one pin to the opposite end of major axis therefore is 9".  Double 
> that and you have a string length of 18".  Did I err somewhere here?
> 
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