hi
i didn't understand a thing but wharever. Here is an answer.
In line 1 et lune 2, the first XY is the point A(departure) of the line, et the second XY is the point B (arrival)
I hope it helps
Giuliano Franchetto
Student at the l'Ecole Nationale Supérieure des Mines de Saint-Etienne, cycle ISMIN (FRANCE)
