O = Point(xAxis)
c = Circle(O, 1.0)
A, B = Intersect(c, xAxis)
d = Semicircle(A, B)
M = Point(d)
a = OrthogonalLine(M, yAxis)
b = OrthogonalLine(M, xAxis)
C = Intersect(a, yAxis)
D = Intersect(b, xAxis)
e = Segment(M, O)
α = Angle(B, O, M)
f = Segment(M, C)
g = Segment(M, D)