Page 1 - Lesson Note-4-Ch-13 SA and Volume(Sphere)

SAI International School
CLASS - IX

Mathematics
CHAPTER-13: SURFACE AREAS AND VOLUMES

Lesson Note-4 [SPHERE]

Sphere

A sphere is a three-dimensional figure (solid shape), which is made up of all points in
the space, which lie at a constant distance called Radius, from a fixed point called
the Centre of the sphere.

Its shape is completely round like a ball.

It has the same curved and total surface area.

Sphere

Let the radius of sphere be ‘r’

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1. Surface area of Sphere(Total) = 4πr square unit.
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2. Volume of Sphere= πr cubic unit
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Hemi sphere

If we cut the sphere in two equal parts then is said to be a hemisphere.
It has two surface areas; one is Curved Surface Area(CSA) and the other is Total
Surface Area(TSA).

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