a parallelogram and parallel lines@@
@There is a parallelogram .Point O is the point of intersection.
AB//PS//CD,AD//QR//BC,PQ//AC//RS

Move point P to find the geometric quality of the pink line length (PS+SR+RQ+QP).
@You can also move points (A,B,C,P) on CABRI.

Download CABRIU data (d37) from here.