f(x, y) = x^(2) + y^(2)
A: (2, 1, f(2, 1))
g: y = 1
r1 = IntersectPath(g, f)
h: x = 2
r2 = IntersectPath(h, f)
A0: (2, 1, 0)
v = Vector(A0, A)