Suppose u(x, y) is a solution of the minimal surface equation in R2 Wy I tutu, + = 0. ar ay 1 +uz tu2 Define the following functions f(x, y), g(r, y) and h(x, y): f = (1 + up)/v, g = Ugly/v, h = (1+ u,)/v where v(x, y) = /1+ ur + us. Show that of 09 - 0. and ag ah = 0. ay ay ar