Page 1 - Lesson Notes-Ch.13 SA and Volumes(Cuboids and Cubes)
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SAI International School
CLASS - IX
Mathematics
CHAPTER-13: SURFACE AREAS AND VOLUMES
Lesson Notes-1
SURFACE AREA AND VOLUME OF CUBOIDS AND CUBES
INTRODUCTION:
Plane figures
The figures which we can draw on a piece of paper or which lie on a
plane are called Plane figures.
Example - Circle, Square, Rectangle etc.
Solid figures
The 3D shapes which occupy some space are called Solid figures or
Solids.
Example - Cube, Cuboid, Sphere, Cone etc.
Surface Area
The sum of the area of all the faces of the solid shape is the total
surface area of that figure. The unit of surface area is a ‘square’ unit.
VOLUME:
Space occupied by any solid shape is the capacity or volume of
that figure. The unit of volume is a ‘cubic’ unit.
If an object is solid, then the space occupied by such an object is
measured and is term as the Volume of the object. On the other
hand, if the object is hollow, then interior is empty, and can be
filled with air, or some liquid that will take the shape of the
container. In this case,the volume of the substance that can fill
the interior is called the capacity of the container .
In general, the volume of an object is the measure of the space it
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