David Fontaine wrote:

> That would be a parabola (actually, a catenoid, but parabola suffices and
> mathworld.wolfram.com is down).
>
> To find arc length is difficult...

1) Find parametric equations for the parabola
  xt = t
  yt = at^2 + bt + c
2) Differentiate these equations
  x't = 1
  y't = 2at + b
3) Use pythagorean theorem to find how fast (x,y) is moving with respect to t
  sqrt(4a^2t^2 + 4abt + b^2 + 1)
4) Integrate to get an equation for arc length

It helps to have values of a, b and c before you start...

--
David Fontaine  <dav### [at] faricynet>  ICQ 55354965
My raytracing gallery:  http://davidf.faricy.net/

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