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Topic: rational n-gon inscribed in a unit circle
Replies: 59   Last Post: Dec 19, 2013 12:56 AM

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quasi

Posts: 10,315
Registered: 7/15/05
Re: rational n-gon inscribed in a unit circle
Posted: Dec 14, 2013 2:29 PM
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quasi wrote:
>quasi wrote:
>>
>>A revised definition ...
>>
>>Call an n-gon "rational" if all edge lengths are rational.
>>
>>Call an n-gon "rational-unit-cyclic" if it's rational and
>>can be inscribed in a unit circle.
>>
>>Call an n-gon "primitive-rational-unit-cyclic" (PRUC) if it's
>>rational-unit-cyclic and, for any reordering of the edges, no
>>diagonal has rational length.
>>
>>Note: In my previously posted tentative definition, there were
>>additional requirements, namely: n > 3, pairwise distinct edge
>>lengths, and no edge length equal to 2. Those additional
>>requirements have now been dropped.
>>
>>Any rational-unit-cyclic triangle is PRUC, and the class of all
>>such triangles can be represented parametrically.
>>
>>There exist PRUC quadrilaterals. For example, the quadrilateral
>>found by Richard Tobin with sides 8,36,57,62 and radius 32 is
>>a PRUC quadrilateral scaled by a factor of 32.
>>
>>There are other PRUC quadrilaterals as well, but there's no
>>clear pattern that I can see relating the numerical values of
>>the edge lengths. It's not clear how to generate them except by
>>brute force search.
>>
>>So that's the question.
>>
>>For some n > 3, either general or specific, is there some
>>subclass of the class of PRUC n-gons which can be generated
>>by a method other than brute force search? Perhaps a parametric
>>representation or a recursion?
>>
>>In the meantime, the current search methods might help by
>>revealing a pattern for some subclass of PRUC n-gons.

>
>I haven't yet found a PRUC pentagon.
>
>I have my search program running, but so far, nothing.


Still nothing, so based on that, I'll revive one of my previous
conjectures for the special case n = 5 ...

Conjecture:

If a pentagon inscribed in a unit circle has rational edge
lengths, then for some reordering of the edges within the
circle, two vertices are diametrically opposite.

quasi


Date Subject Author
12/10/13
Read rational n-gon inscribed in a unit circle
quasi
12/10/13
Read Re: rational n-gon inscribed in a unit circle
ross.finlayson@gmail.com
12/10/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/11/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/11/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/11/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/12/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/12/13
Read Re: rational n-gon inscribed in a unit circle
Helmut Richter
12/12/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/11/13
Read Re: rational n-gon inscribed in a unit circle
scattered
12/11/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/11/13
Read Re: rational n-gon inscribed in a unit circle
fom
12/11/13
Read Re: rational n-gon inscribed in a unit circle
fom
12/11/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/11/13
Read Re: rational n-gon inscribed in a unit circle
fom
12/11/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/11/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/12/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/12/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/12/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/12/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/12/13
Read Re: rational n-gon inscribed in a unit circle
Brian Q. Hutchings
12/13/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/13/13
Read Re: rational n-gon inscribed in a unit circle
Brian Q. Hutchings
12/12/13
Read Re: rational n-gon inscribed in a unit circle
Thomas Nordhaus
12/12/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/12/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/12/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/12/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/12/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/13/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/13/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/13/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/13/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/13/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/13/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/13/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/13/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/12/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/13/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/13/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/13/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/14/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/14/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/14/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/14/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/14/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/15/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/15/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/15/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/15/13
Read Re: rational n-gon inscribed in a unit circle
David Bernier
12/15/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/18/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/18/13
Read Re: rational n-gon inscribed in a unit circle
ross.finlayson@gmail.com
12/19/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/14/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/14/13
Read Re: rational n-gon inscribed in a unit circle
quasi
12/14/13
Read Re: rational n-gon inscribed in a unit circle
Richard Tobin
12/14/13
Read Re: rational n-gon inscribed in a unit circle
ross.finlayson@gmail.com
12/15/13
Read Re: rational n-gon inscribed in a unit circle
Brian Q. Hutchings

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