1/3 The bottom area multiplied by the height is the volume formula of a cone, and the expansion of the cone is a sector. In order to calculate the surface area of a cone, it is necessary to know how many degrees the central angle of the sector is. If the central angle is known, the surface area of the cone can be calculated.

If the degree of the central angle is known, the area is as follows:

The surface area of the cone = the bottom area+the square of the length of the hypotenuse of the cone * ∏ * (the degree of the cone /360)

Bottom area = square of bottom radius * ∏.