surface area and volume

2. DIFFERENT TYPES
OF SHAPES

3. • CUBOID
• CUBE

4. • HEMISPHERE
• SPHERE

5. • CONE
• CYLINDER

7. When a plane through the centre of a sphere
cuts it into two equal parts is called a
hemisphere.

8. FORMULAE’S

9. EXAMPLE -1
A hemispherical dome of a building needs to
be painted. If the circumference of the base
of the dome 15.8,find the cost of painting
it,given the cost of painting Rs. 10per
100cm.square.

10. SOLUTON-1
2x22/7x79/10x79/10
2
= 392.30 (cm )
=3920.30
=Rs.1,96,150 (Ans)

11. EXAMPLE-2
The circumference of the edge of a
hemispherical bowl is 132cm.Find the
capacity of the bowl.

12. SOLUTION-2
Circumference = 2 r
132
=2x22/7xr
R= 132x7/2x22
R=21
Capacity=

13. 2/3x22/7x21x21x21
3
= 19404 cm (Ans)

14. EXAMPLE-3
Find the volume ,curved surface
area and the total surface area of
hemisphere of diameter 7 cm?

15. SOLUTION -3
)
=2 x14x14cm.square
=(392 )cm.square
=2/3x22/7x7/2x7/2x7/2 cm.cube
539/6 = 89.83cm.cube
2x22/7x2/7/2
=77cm.square

16. 3x22/7x7/2x7/2
=115.5cm.square. (Ans)

17. 
• A hemisphrical bowl is made up of steel,0.75m
thick.The inner radius of the bowl is 15m .
Find the outer curved surface area ?

18. 
• R = thickness + inner radius
• = 0.75 + 15 = 15.75
= 2x22/7x15.75x15.75
= 1559.25m.square.

19. EXAMPLE-5
• The volume of hemisphere is 5544cm.square.
Find its radius ?

20. SOLUTION -5
•
•
•
•
•
•
3
5544
= 2/3x22/7x r
3
5544x7/2x22= r
cube root of r =756
r = 19.63cm.cube.

21. EXAMPLE- 6
• If diameter of a solid hemisphere is half then
its total surface area ill be decreased by 75%.

22. SOLUTION - 6
• Let diameter be = x
• Radius = x/2
•
•
•
•
3
(x/4) = 3 r.square./16
change in T.S.A original-new/originalx100
3 r.square / 4 -3 r.square /16 x 100
4

23. r.square – 3
• 12
square/4
• 9 x.square/16/3
• 3/4x100
• = 3x25
• = 75% (Ans)
r.square/16/3 r
r.square/4

24. QUESTION - 1 & 2
• Find the volume of hemisphere whose radius
is 21 cm ?
• ANS. 19404 cm.cube
Find the total surface area and the curved
surface area whose radius is 7 cm?
ANS. 462 cm. square
308 cm .square

25. THANKYOU