Given a point P, the pedal triangle of P is the triangle whose polygon vertices are the feet of the perpendiculars from P to the side lines. The pedal triangle of a triangle with trilinear coordinates α:β:γ and angles A, B, and C has trilinear vertex matrix [0 | β + α cos C | γ + α cos B α + β cos C | 0 | γ + β cos A α + γ cos B | β + γ cos A | 0] (Kimberling 1998, p. 186), and is a central triangle of type 2.

antipedal triangle | Fagnano's problem | orthic triangle | pedal circle | pedal line