A = (0, 1)
B = (1, 1)
C = (1, 0)
D = (0, 0)
a = Segment(A, B)
b = Segment(C, B)
c = Segment(C, D)
d = Segment(D, A)
e = CircleArc(D, C, A)
T = Point(e)
f, g = Tangent(T, e)
M = Intersect(a, f)
N = Intersect(f, b)
MN = Distance(M, N)
AM = Distance(A, M)