A = (7, 2, 0)
f(x, y) = If[5 - (x - 9)^(2) / 15 - (y - 5)^(2) / 14 > 1.5 ∧ x ≤ x(A) ∧ y ≥ y(A), 5 - (x - 9)^(2) / 15 - (y - 5)^(2) / 14]
B: (x(A), y(A), f(x(A), y(A)))
fx = Derivative(f, x)
fy = Derivative(f, y)
a: f(x(A), y(A))
b: f(x(A), y(A))
v_x = Vector(B, (x(A) + 2, y(A), f(x(A), y(A)) + (2 * fx(x(A), y(A)))))
v_y = Vector(B, (x(A), y(A) + 2, f(x(A), y(A)) + (2 * fy(x(A), y(A)))))
c = CurveCartesian(x(A), v, f(x(A), v), v, y(A), 12)
d = CurveCartesian(u, y(A), 5 - (u - 9)^(2) / 15 - (y(A) - 5)^(2) / 14, u, 2.5, 10)
C: (11, 4, 0)
v = Vector(A, C)
v_3: (x(v) * v_x) + (y(v) * v_y)
D: (9, 2, 0)
e = Vector(A, D)
E: (7, 4, 0)
g = Vector(A, E)
r: (2 * v_x) + v_y
B' = Translate(B, r)
u = Vector(B, B')
A2 = NaN
t(x, y) = If[abs(x - x(A)) < 3 ∧ abs(y - y(A)) < 3 ∧ y ≥ (y * A2), (2 * f(x(A), y(A))) + ((2 * fx(x(A), y(A))) * (x - x(A))) + ((2 * fy(x(A), y(A))) * (y - y(A)))]