A = (1.56, 0.32)
B = (4.96, 1.24)
f = Line(A, B)
C = (4.2, -1.44)
g = Line(B, C)
h = Line(C, f)
i = Line(A, g)
D = Intersect(h, i)
α = Angle(A, B, C)
E = Point(h)
F = Point(g)
β = Angle(E, C, B)
γ = Angle(D, C, F)
δ = Angle(C, D, A)
etape = 5 (slider from 0 to 5, step 1)