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  of is the isogonal conjugate of the centroid .
, , 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.