A solar water heater is made from a long sheet of metal bent so that the cross sections are parabolic. A long tube of water is placed inside the curved surface so that the height of the tube is equal to the focal length of the parabolic cross section. In this way, water in the tube is exposed to maximum heat. 5 ft 4 ft a. Determine the focal length of the parabolic cross sections so that the engineer knows where to place the tube. b. Use a coordinate system with origin at the vertex of a parabolic cross section and write an equation of the parabola.