Define L rucksack any direct from the nasen drag a straight line perpendicular to L N cut a straight line L at point Q N call that perpendicular straight line L.
L designated symbolized by a line from the origin to any straight line perpendicular to L N cut straight to the point Q L N that run perpendicular line L.
The L a straight line from the origin of the line at any N perpendicular to the L cut with straight L point Q call N that perpendicular line of line L.