A = Intersect(xAxis, yAxis)
c = Circle(A, 1)
B = Intersect(c, xAxis, 2)
C = Point(c)
d = CircleArc(A, B, C)
a = Segment(A, C)
b = Segment(C, (x(C), 0))
e = Segment(C, (0, y(C)))
f: y(C)
D: (d, f)
g: x(C)
E: (d, g)