O = (0, 0)
A = (1, 0)
B = (0, 1)
a = Ray(O, A)
b = Segment(O, B)
C = CircleArc(O, A, B)
M = Point(C)
d = CircleSector(O, A, M)
c = Segment(O, M)
e = OrthogonalLine(M, c)
N = Intersect(e, a)
poly1, n, o, m = Polygon(O, M, N)
p: poly1 - d
texte1 = Text(p, (1.3, 0.2))
β = Angle(A, O, M)