1. Area (compound figure)

2. How can we calculate a rectangle’s area?
Width
(W)
Area = length x width
= L x W
Length (L)
5cm
10cm

3. How can we calculate a square’s area?
Length (L)
5cm

4. Work out the area of each figure
2cm
3cm
4cm
3cm

5. How can we calculate the area of this compound figure?

6. How to calculate the area of this compound figure?

7. How to calculate the area of this compound figure?

8. 1) Cut 2) Calculate 3) Add

9. How to calculate the area of this compound figure?
Make the shape whole
2) Calculate area of whole
3) Calculate area of missing part
4) Subtract

10. Practice: 7m 3m
10m 5m

11. If we cut a rectangle from the square, what’s the area of blue part?
16cm
9cm
4cm 16 cm

12. What’s the area of shaded part?5
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13. What’s the area of this figure?7 10 3

14. What’s the area of this figure?4 2 10

15. Challenge:
If we add 4m to the length of a rectangle, then its area will increase by 20m2
If we subtract 2m from the width of the rectangle, then its area will decrease by 12m2
What is the original area of the rectangle?

16. Challenge:
If we add 4m to the length of a rectangle, then its area will increase by 20m2 4m 2m
If we subtract 2m from the width of the rectangle, then its area will decrease by 12m2

17. Thank you!