Special about this point is that it lies on QL-L3, the QL-Pedal Line.
Besides that it has a distance relation with the M3D Line (QL-L9).
(a2 m n - SB l m - SC l n) (3 m n - l m - l n)
Sa (m2-n2)2 - Sb (l2-n2) n2 - Sc (l2-m2) m2
- QL-P19 lies on this line:
- QL-P19.QL-P20 // QL-P7.QL-P21
- QL-P19 lies on QL-L3, the QL-Pedal Line.
- QL-P19 is the Quadrangle Centroid of the “flat quadrangle” formed by the 4 projection points of QL-P1 (collinear on QL-L3, the QL-Pedal Line) on the basic lines of the Reference Quadrilateral.
- d(QL-P19, QL-L9) = ¾ * d(QL-P8, QL-L9)