Déplacer le point M 
et observer la position des droites (EH) et (GF)

A = (0, 0)
B = (10, 0)
poly1, a, b, c, d, C, D = Polygon(A, B, 4)
M = (3.4207367193825937, 3.8600627465202386)
e = Line(M, a)
f = Line(M, d)
E = Intersect(e, d)
F = Intersect(e, b)
G = Intersect(f, a)
H = Intersect(f, c)
g = Line(E, H)
h = Line(G, F)