**Important Concepts and Formulas**

1. We can find the surface area of an
object formed by combining any two of the basic solids, namely, cuboid, cube,
cone, cylinder, sphere and hemisphere. We can add the surface areas of all the
solids from which it is formed.

To know the basic formulas of surface areas of different
solids ----- Click Here!

2. To find the volume of objects formed
by combining any two of a cuboid, cone, cylinder, sphere and hemisphere, we can
add the volumes of the objects by which it is formed.

To know the basic
formulas of volumes of different solids ----- Click Here!

3. From a right circular cone, which is
sliced through by a plane parallel to its base, if the smaller conical portion
is removed, the resulting solid is called a

**of a right circular cone.***frustum*
4. The formulas involving the frustum of
a cone are as follow:

5. Volume of a frustum of a cone is
given by:

6. Curved surface area of a frustum of a
cone = Ï€

*l*(*r*+_{1}*r*), where_{2}*l*is given by:
7. Total surface area of frustum of a
cone = Ï€

*l*(*r*+_{1}*r*) + Ï€(_{2}*r*+_{1}^{2}*r*), where_{2}^{2}*h*= vertical height of the frustum,

*l*= slant height of the frustum,

*r*and

_{1}*r*are radii of the two bases (ends) of the frustum.

_{2}