Concise Selina Solutions for Class 9 maths Chapter 21 Solids

In mathematics, solid geometry is the traditional name for the geometry of three-dimensional Euclidean space. Stereometry deals with the measurements of volumes of various solid figures, including pyramids, prisms and other polyhedrons; cylinders; cones; truncated cones; and balls bounded by spheres. Solid shapes can be drawn on a flat surface, which is known as the two-dimensional representation of a three-dimensional solid. Anything which occupies space and has a definite shape is called a solid. The space occupied by a solid is called its volume. The sum of the areas of all the surfaces of a solid is called it is the surface area or its total surface area.