You have explored so far two dimensional shapes i.e. having only length and breadth like polygons,
circles etc. are planar shapes. However, the experience in the real world reveals that every object
has three dimensions i.e. length, breadth, height and occupy space. Such objects which occupy space
are called solids.
To have deeper understanding, E.g. a brick used in construction, which can not
be contained in a single plane and it has dimensions like- length 10 in, breadth 5 in and height
4 in or so. Therefore, no single plane can contain such it in totality. Other examples, having
the common 3D shapes with which you should be familiar are: cubes, prism, cylinder, pyramid etc.
Apart from important properties of such objects, method to calculate their surface area and volume
are also covered in this chapter.

This lesson explains using Video the important properties and relationships that should help you to solve the problems and help in doing Geometry homework.