r1: 5.8
r2: 9.2
r3: 13.7
O: (0, 0)
c = Circle(O, r1)
d = Circle(O, r2)
e = Circle(O, r3)
a = Sphere(O, r1)
g(x, y) = x^(2) + y^(2) - r2^(2) > 0 ∧ x^(2) + y^(2) - r3^(2) < 0