A Cone is a three-dimensional shape with a circular base tapering
to a point (the vertex).
The area A of the curved surface of a cone is : π
x radius x slant height
A = π x r x l
The slant height is the distance along the surface of the
cone from the vertex to the base.
More precisely, it is the solid figure bounded by a plane
base and the surface (called the lateral surface) formed by
the locus of all straight line segments joining the apex to
the perimeter of the base.
The term cone sometimes refers just to the surface of this
solid figure, or just to the lateral surface. The axis of
a cone is the straight line (if any), passing through the
apex, about which the lateral surface has a rotational symmetry