Quadrilatère complet
Author: Patrice Debart

A = (1, -4)
B = (6, -2)
C = (5, 0)
D = (3, 1)
dAB = Line(A, B)
dCD = Line(D, C)
dAD = Line(A, D)
dBC = Line(B, C)
E = Intersect(dAB, dCD)
F = Intersect(dAD, dBC)
AE = Segment(A, E)
AF = Segment(A, F)
BF = Segment(B, F)
DE = Segment(D, E)