1. Finding the Area of a Rectangle

2. Objectives
To calculate areas of rectangles
To calculate areas of polygons made of rectangles

3. Area is the measure of how much space a shape takes up
Area is the measure of how much space a shape takes up. We measure it in squares such as square centimetres or metres etc.
1 cm
This rectangle takes up 28 squares.
It has an area of 28 square centimetres
28 cm2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

4. It could take a long time to cover shapes in squares
It could take a long time to cover shapes in squares. Luckily there is an quicker way.
7 cm
4 cm ×
= 28 cm2

5. Area of a rectangle = length × breadth
Use this formulae to find the area of rectangles.
length
breadth
Area of a rectangle = length × breadth

6. Can you find the areas of these rectangles?
5 cm
3 cm
2 cm
7 cm
15 cm2
14 cm2
7 m
49 m2

7. Can you think of a way to find the area of this shape?
5 cm
6 cm
7 cm
3 cm
12 cm

8. Split the shape into rectangles?
5 cm
6 cm
7 cm
3 cm
12 cm

9. Find the area of each rectangle?
5 cm
5 × 6 = 30 cm2
7 × 3 = 21 cm2
6 cm
7 cm
3 cm

10. Add the areas together to find the area of the complete shape?
= 51 cm2
30 cm2
21 cm2

11. Can you find the areas of these shapes?
11 cm
5 cm
7 cm
4 cm
2 cm
6 m
22 m2
3 m
4 m
43 cm2
1 m
4 m

12. Clue: Take the area of the hole from the area of the whole!
Here is a challenge can you work out the area of this shape with a hole in it?
2 cm
5 cm
5 cm
10 cm
Clue: Take the area of the hole from the area of the whole!
50 cm2 – 10 cm2 = 40 cm2

13. Area of a rectangle = length × breadth
Remember:
Area of a rectangle = length × breadth
length
breadth
Split more complicated shapes into rectangles and find the area of each rectangle then add them together.
Over to you.