Lester's theorem

The set of Lester, named after June Lester, is a statement of plane Euclidean geometry, which in any, not isosceles triangle, the two Fermat points, the center of the Feuerbach circle and the circumcenter are konzyklisch, ie lie on a circle.

The center of that circle has the Kimberling number X ( 1116) and the barycentric coordinates:

Nine-point circle Mathematica Wolfram Research
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