# Basic Parameters of the Second Fermat Point

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Given a triangle , construct three equilateral triangles , , on the insides of edges , , . Then the lines , , converge at the second Fermat point, the Kimberling center [1].

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Let , , be the exact trilinear coordinates of with respect to and set .

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.

Then

,

,

.

You can drag the vertices , and .

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Contributed by: Minh Trinh Xuan (January 2023)
Open content licensed under CC BY-NC-SA

## Details

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.

Standard barycentric coordinates of a point with respect to a reference triangle have a sum of 1.

Reference

[1] C. Kimberling. "Encyclopedia of Triangle Centers." (Aug 9, 2022) faculty.evansville.edu/ck6/encyclopedia.

## Permanent Citation

Minh Trinh Xuan

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