2. (a) The equation 4 + y - 1 represents a cylinder with elliptical cross sections in planos perpen dicular to the z-axis. Find a vector u perpendicular to which the cylinder has circular cross sections (b) Find an equation for the surface consisting of all points (r,y,z) that are three times as far from the point (0,0,9) as they are from the plane : = 1. Sketch and identify the surface. Write an equation in spherical coordinates for the obtained surface