h(x, y) = 5 - abs(5 - x)
A = (5, 5, 0)
P_0: (x(A), y(A), h(x(A), y(A)))
a: h(x(A), y(A))
b: h(x(A), y(A))
g(x, y) = 5 - abs(5 - y)
f(x, y) = If[x ≥ 0 ∧ x ≤ 10 ∧ y ≤ 10 ∧ y ≥ 0, If[h(x, y) > g(x, y), h(x, y), g(x, y)]]