1. Starter Which of these shapes has the greatest perimeter?
Which has the smallest?
What is each perimeter in terms of d? d

2. Answers Square has 4 sides of length d 4d Hexagon has 6 sides of ½d 3d

3. Answers Square has 4 sides of length d 4d Hexagon has 6 sides of ½d 3d
Circle is between 3d and 4d πd

4. Area Which of these shapes has the greatest area?
Which has the smallest?
What is the area in terms of r?
r r r

5. Area Large square is 2r x 2r = 4r2 Small square is half of this = 2r2

6. Area Large square is 2r x 2r = 4r2 Small square is half of this = 2r2
Circle has area in between 2r2 and 4r2

7. Circles
A circle has radius r.

8. Circles
Rearrange the sectors.

9. Circles Consider the lengths. So the length of this side is πr
Circumference of circle = 2πr
Length of half circumference = πr

10. Circles Consider the lengths. πr So the height is r
Radius of circle = r

11. Circles Consider the area. r πr
Area of shape is close to area of parallelogram = base x height = πr x r = πr2
Hence the area of a circle is = πr2

12. Circles A circle has radius r and diameter d.
Circumference of a circle
C = πd
Area of a circle
A = πr2

13. Calculate the area and perimeter of the following shapes:
r = 6cm
r = 7cm
d = 4cm
r = 4cm
r = 1.5cm
1/8
r = 4cm
r = 2cm
r = 6cm
60°
r = 3cm
45°
165°
r = 3cm
r = 8cm
225°
r = 5cm

14. Answers A = 6.28cm² A = 14.14cm² A = 12.57cm² A = 38.48cm²
P = 10.28cm P = 15.42cm P = 14.28cm P = 25.00cm
A = 28.27cm² A = 37.70cm² A = 3.53cm² A = 1.57cm²
P = 21.42cm P = 26.85cm P = 7.71cm P = 5.57cm
A = 3.53cm² A = 33.51cm² A = 17.67cm² A = 36.00cm²
P = 8.36cm P = 24.38cm P = 17.78cm P = 24.40cm

15. Calculate the area and perimeter of this compound shape:
8cm
12cm

16. Calculate the area and perimeter of this compound shape:
8cm
Area of rectangle = b x h
12cm
Area of rectangle = 8 x 12
96cm²
Area of rectangle = 96cm²

17. Calculate the area and perimeter of this compound shape:
56.55cm²
8cm
Area of semi-circle = π x r² ÷ 2
12cm
Area of semi-circle = π x 6²÷ 2
96cm²
Area of semi-circle = 56.55cm²

18. Calculate the area and perimeter of this compound shape:
56.55cm²
8cm
Area of semi-circle = π x r² ÷ 2
12cm
Area of semi-circle = π x 4²÷ 2
96cm²
Area of semi-circle = 25.13cm²
25.13cm²

19. Calculate the area and perimeter of this compound shape:
56.55cm²
8cm
Total area =
12cm =
96cm²
177.68cm²
25.13cm²