(8) Let S be an oriented regular surface and let p E S. Define the "height" function :S R such that f(q) = {q - p, N(p)) for all qe S. Prove that p is a critical point of f and that Hess()p(v) = II(v) for all v ET,S. (8) Let S be an oriented regular surface and let p E S. Define the "height" function :S R such that f(q) = {q - p, N(p)) for all qe S. Prove that p is a critical point of f and that Hess()p(v) = II(v) for all v ET,S