The document discusses calculating the surface areas of circular solids like cylinders and cones. It provides formulas for finding the surface area of a cylinder and a cone. For cylinders, the surface area is equal to the area of the two circular ends plus the area of the curved side surface. For cones, the surface area is the area of the circular base plus the area of the lateral curved surface, which can be calculated using the ratio of the sector area to the total circular area and the slant height.