Class 9 Maths Surface Areas Volumes | Introduction |

**Introduction **

Area is the amount of space inside a boundary of a 2D object.

**Surface area** of a solid 3D object is the measure of the total area that a surface of an object occupies. It is measured in m^{2}, cm^{2} etc

We generally talk about inner surface area & outer surface area.

Surface area is typically used to determine cost of painting for a given 3D object.

**Volume** is the quantity of 3D space enclosed by some closed boundary. It is measured in m^{3}, cm^{3}, ltr etc.

It is typically used to determine quantity of liquid, air, grains etc in a 3D container.

We will study Surface Area & Volume for Cube, Cuboid, Sphere, Cone and Cylinder.

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