The formula πrs represent the lateral surface area of the cone.
Lateral surface area--
The lateral surface area of a solid ( i.e. a three dimensional object) is the area of all the sides of the solid excluding the area of the base as well as top of the solid.
If r is the radius of the cone and s is the slant height of the cone then the lateral surface area of the cone is given by the formula:
[tex]Lateral\ surface\ area=\pi rs[/tex]