Use traces to sketch the surface. (If an answer does not exist, enter DNE. Select Update Graph to see your response plotted on the screen. Select the Submit button to grade your response.) 16x2 + 9y2 + 9z2 = 144 (Write an equation for the cross section at z = 0 using x and y.) (Write an equation for the cross section at y = 0 using x and z.) (Write an equation for the cross section at x = 0 using y and z.) Identify the surface. elliptic cone parabolic cylinder hyperboloid of two sheets ellipsoid elliptic paraboloid hyperbolic paraboloid hyperboloid of one sheet elliptic cylinder