Volume of Cone

The text book definition of pyramid and cone can be written as below.

Pyramid	Cone
Pyramid is a solid formed by polygon base and all other triangles faces with a common vertex.	Cone is a solid formed by circular base and rays emanating from a fixed point (vertex) and passing through the base.
In the limit, as the number of faces in pyramid approaches to infinity, the shape is a cone.	There are four types of cones: circular, elliptical, right, and oblique. A cone is also a pyramid, and it is the fifth type as n = ∞. In the figure left, keep sliding the number of sides and see that as the number of triangular faces increases, the pyramid begins to look more and more like a cone.

Click here → The Interactive Applet for Animated Pyramid to cone

In the assumption as explained above, we can understand cone as a pyramid with circular base.

In the premises, the volume of cone is

              V= 1/3 * B* h

However,

We can also use cavalieri's principle to find the volume of cone. 

The detail is shown below.