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Re: triangles in circles

  • To: mathgroup at
  • Subject: [mg26839] Re: triangles in circles
  • From: "Paul Lutus" <nospam at>
  • Date: Thu, 25 Jan 2001 01:13:18 -0500 (EST)
  • References: <94ma2t$>
  • Sender: owner-wri-mathgroup at

"Tom De Vries" <tdevries at> wrote in message
news:94ma2t$3pi at
> Hello all,
> I'm teaching a high school math class and we are doing permutations and
> combinations.  One of the "standard" questions is ..."given a certain
> of points located around a circle, how many triangles can be formed...."
> The simple line below creates a circle with 5 points arranged around it.
> Could someone help me with a way to generate the lists of points that
> create all the triangles.   I know that for more points it would get kind
> messy, but I wanted to actually draw all the triangles as I thought it
> be an interesting graphic...
> Thanks for any help you might have....
> n = 5;
> ptlist = Table[{Cos[i 2 \[Pi]/n], Sin[i 2 \[Pi]/n]}, {i, 1, n}];
> Show[Graphics[{
>       Circle[{0, 0}, 1],
>       {PointSize[0.02], Point /@ ptlist}
>       }], AspectRatio -> Automatic]

Here is a starting point -- it groups your five points into unique sets of


n = 3;

qlist = {a,b,c,d,e}



Paul Lutus

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