Basic Parameters of the First Fermat Point

Given a triangle , construct the three exterior equilateral triangles , , . Then the lines , , intersect at the first Fermat point [1].
Let , , be the exact trilinear coordinates of with respect to and set .
Let , , be the side lengths ; let , , be the circumradius, inradius and semiperimeter of ; let ; and set , , , to be the Conway notation, where is the Brocard angle.
You can drag the vertices , and .


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A triangle center is said to be even when its barycentric coordinates can be expressed as a function of three variables , , that all occur with even exponents. If the center of a triangle has constant barycentric coordinates, it is called a neutral center (the centroid is the only neutral center). A triangle center is said to be odd if it is neither even nor neutral.
[1] C. Kimberling. "Encyclopedia of Triangle Centers." (Aug 18, 2022)
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