CLASS IX MATHS PPT

Volume and surface area

1. PowerPoint presentation

2. What it is

3. it is rectangle

4. What it is

5. it is square

6. What it is

7. it is triangle

8. What it is

9. it is hexagon

10. Which type of figures these are

11. These are plane figures or 2 dimensional figures

12. What it is

13. it is cuboid

14. What it is

15. it is cube

16. What it is

17. it is cylinder

18. Which type of figures these are

19. These are called solid figures or 3d figures

20. HOW THESE SOLID FIGURE ARE MADE UP OF

21. THESE SOLID FIGURES ARE MADE UP OF PLANE SURFACES OR PLANE FIGURES

22. Side 2 Bottom Back Top Side 1 Front Side 2 Bottom Back Top Side 1 Front Length (L) Breadth (B) Height (H) Cuboid

23. WHEN WE TAKE THE AREA OF THESE PLANE FIGURES AS A SUM , THEN IT IS CALLED THE SURFACE AREA OF THE SOLID FIGURES.

24. NOW LET US DISCUSS THAT HOW TO FIND THE SURFACE AREAS OF CUBOID

25. The net L L L L B H H H H L B B B B B H H

26. H B L H B H L L L H B L H B H L L Total surface Area

27. Total surface Area = L x H + B x H + L x H + B x H + L x B + L x B = 2 ( LxB ) + 2( BxH ) + 2( LxH ) = 2 ( LB + BH + LH )

28. NOW LET US DISCUSS ABOUT THE SURFACE AREA OF CUBE

29. WHAT IS THE DIFFERENCE BETWEEN A CUBOID AND A CUBE

30. THE NET FOR THE CUBE

31. Cube L L L Total surface area = 2(LxL) + 2(LxL) + 2(LxL) = 6L 2

32. AREA OF FOUR WALLS . THIS IS ACTUALLY THE AREAS OF THE SURFACES WHERE THE HEIGHT IS INVOLVED . THIS AREA IS ALSO CALLED THE LATERAL SURFACE AREA IN CASE OF CYLINDER THIS PART IS CALLED THE CURVED SURFACE AREA BECAUSE THIS PART IS CURVED IN CASE OF CYLINDER

33. LSA OF CUBOID=2(L*H) +2(B*H) = 2(L+B)H LSA OF CUBE =L 2 + L 2 + L 2 + L 2 = 4 L 2

34. PRACTICE QUESTION 1. FIND THE SURFACE AREA OF CUBOIDAL BOX HAVING THE MEASUREMENT 10cm X 5cm X2cm.

35. SOLUTION S A OF CUBOID = 2(LB+BH+HL) = 2(10*5 + 5*2 + 2*10) = 2(50+10+20) = 2*80 =160 CM 2 .

36. PRACTICE QUESTION 2 FIND THE SIDES OF A CUBE WHOSE SURFACE AREA IS 600 CM 2 .

37. SOLUTION S A OF CUBE = 6a 2 600cm 2 = 6 a 2 100 cm 2 = a 2 TAKING SQUARE ROOT BOTH SIDE 10 cm = a EACH SIDE = 10cm.

38. LEARNING ACHIEVEMENT TEST 1. APLASTIC BOX 1.5 cm LONG 1.25 cm WIDE AND 65 cm IS TO BE MADE. IT IS OPENED AT THE TOP. IGNORING THE THICKNESS OF THE PLASTIC SHEET, DETERMINE : (A) THE AREA OF THE SHEET REQUIRED FOR MAKING THE BOX (B) THE COST OF THE SHEET FOR IT, IF A SHEET MEASURING 1m 2 COSTS Rs 20. 2. THE LENGTH , BREADTH AND HEIGHT OF A ROOM ARE 5m, 4m AND 3m RESPECTIVELY. FIND THE COST OF WHITEWASHING THE WALLS OF THE ROOM AND THE COST OF CEILING AT THE RATE OF Rs 7.50 PER m 2 . 3. THE FLOOR OF A RECTANGULAR HALL HAS A PERIMETER 250m. IF THE COST OF PAINTING THE FOUR WALL AT THE RATE OF Rs 10 PER m 2 IS Rs 15000, FIND THE HEIGHT OF THE HALL.

39. Home Assignment DISCUSS ABOUT THE DIAGONALS OF CUBOID AND CUBE

40. THANK YOU