Surface Area formula of a cylinder: S.A = 2 × Area of base + Perimeter of base × Height of prism = 2r² + 2rh = 2(10)² + 2(10)(100) {We took 10 ft as the radius because the diameter is 20 ft, so the radius is half the diameter} = 200 + 2000 = 2200 ft² (in terms of ) = 6911.5 ft² (to the nearest tenth)