What is the surface area of a cone with diameter 28cm and height 22cm

The surface area of a cone is : pi•r•slant height + pi•r^2 If d=28 then r=14 Use the pythagorean theorem to find the slant height c^2 = 14^2 + 22^2 C^2 = 680 C = 26.08 (rounded) Pi•14•26.08 + 196pi = 1,762.67 squared cm