B = Point(xAxis)
A = Point(xAxis)
c = Semicircle(B, A)
M = Point(c)
b = Line(M, xAxis)
N = Intersect(c, b, 2)
poly1, n, b_1, a, m = Polygon(N, B, A, M)
AB = Distance(A, B)
MN = Distance(M, N)
AM = Distance(A, M)
BN = Distance(B, N)
AMNB: AB + MN + AM + BN