The angle bisectors of a triangle intersect at the incenter . The isogonal conjugate of a point is found by reflecting the lines , , about the angle bisectors. The symmedian point [1] of is the isogonal conjugate of the centroid .

Let

, , be the exact trilinear coordinates of with respect to ,

,

, , be the side lengths opposite the corresponding vertices and let be the semiperimeter of ,

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 are normalized to a sum of 1.