Let G : A R and H : B R be parametrizations of an oriented surface S C R. Assume there exists a diffeomorphism : U V such that det D > 0, ACU, BC V, B = 4(A), and G(u) = (H0)(u) for u A. Let F be a vector field in R that is continuous on S. Assuming Vue A, (dG dG)(u) = (H H)(&(u)) det Dy(u), prove that SS CF (F G) (G G) d = =SS. CH (F H) (H H) dA provided both integrals exist. In other words, the surface integral is invariant under reparametrization.