X = 3.6 (slider from -1 to 5, step 0.1)
texte1: "X=" + X + ""
A = (0, 0)
B = (3, 0)
c = Circle(A, X + 1)
d = Circle(B, 2 * X - 1)
C, D = Intersect(c, d)
poly1, c_1, a, b = Polygon(A, B, C)
α = Angle(A, C, B)