Question

"Question 1 Find the surface area of a sphere of radius: (i) 10.5 cm (ii) 5.6 cm (iii) 14 cm

Class 9 - Math - Surface Areas and Volumes Page 225"

Answer 1

Sphere:

A sphere is a three dimensional figure which is made up of all points in the space which lie at a constant distance from a fixed point called the centre of the sphere and a constant distance is called its radius.

Surface area of sphere:

For a sphere of radius 'r' ,the  surface area is given by

Surface area of sphere=4πr² sq units.

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Solution:

Given:

(i)  Radius of the sphere (r) = 10.5 cm

Surface area of a sphere= 4πr²

= (4 × 22/7 × 10.5 × 10.5)

= 1386 cm²

 

ii)Given:Radius of the sphere (r) = 5.6 cm

Surface area of a sphere= 4πr²

= (4 × 22/7 × 5.6 × 5.6)

= 394.24cm²

 

 

(iii)Given: Radius of the sphere (r) = 14 cm

Surface area of a sphere= 4πr²

= (4 × 22/7 × 14 × 14)

= 2464 cm²

 

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Hope this will help you....

 

Answer 2

Hi friend ,✋

1)We have ,R=radius of the sphere.=10.5 cm

Surface area=4πr²

={4×22/7×10.5×10.5}cm²

=1386cm²

2))r=radius if the sphere =5.6cm

Surface area=4πr²

=(4×22/7×5.6×5.6)cm²

=394.24cm²


3)r = radius of the sphere =14cm

Surface area =(4×22/7×14×14)cm²

=2464cm²

Hope it helps⛎⛎⛎⛎⛎