Equilateral Ellipse - Formula & References

[Douglasdc]

I did and exam a while ago and one of the questions asked to find a formula for an "equilateral ellipse". In my mind an equilateral ellipse should be a circle, but it seems I am wrong.

I searched online for the term, but didn't find anything useful. Does anyone know what it is, can find a formula and give me some references?

Thanks,
Douglas.

 

[Mark44]

I found a paper by Augustus DeMorgan (http://quod.lib.umich.edu/u/umhistmath/ABN6511.0001.001?rgn=main;view=fulltext, on page 66)

in fact the circle ought to be called \ the equilateral ellipse).

 

[Nidum]

Deleted

 

[Douglasdc]

Thanks Mark. I found the term in some old books as well and they also state that a circle can be called an "equilateral ellipse".

 

[Nidum]

Is it a reference to ellipses with inscribed triangles ?

https://en.wikipedia.org/wiki/Steiner_ellipse

http://mathworld.wolfram.com/TriangleEllipseInscribing.html