Relating Trilinear and Tripolar Coordinates for a Triangle
Given a triangle , the trilinear coordinates of a point are the signed distances to the extended sides. Denote the signed distances of to , and by , and , respectively. If and the incenter are in the same half-plane determined by a side, the signed distance to that side is positive; otherwise, it is negative.
The tripolar coordinates of the point are its distances to the vertices of the triangle, given by , and .
The Conway triangle notation relates the sides to twice the area of the triangle, denoted by :
, , , .
These definitions imply the following formulas between the trilinear and tripolar coordinates: