Area and Circumference.pptxArea and Circumference.pptxArea and Circumference.pptxArea and Circumference.pptxArea and Circumference.pptx

Area and Circumference.pptxArea and Circumference.pptxArea and Circumference.pptxArea and Circumference.pptxArea and Circumference.pptxArea and Circumference.pptxArea and Circumference.pptxArea and Circumference.pptx

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

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

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

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

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

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

7. Circles A circle has radius r .

8. Rearrange the sectors. Circles

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

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

11. Area of shape is close to area of parallelogram = base x height = π r x r = π r 2 r π r Hence the area of a circle is = π r 2 Consider the area. Circles

12. r d A circle has radius r and diameter d. Circumference of a circle C = π d Area of a circle A = π r 2 Circles

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

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 12cm Area of rectangle = b x h Area of rectangle = 8 x 12 Area of rectangle = 96cm² 96cm²

17. Calculate the area and perimeter of this compound shape: 8cm 12cm 96cm² Area of semi-circle = π x r ² ÷ 2 Area of semi-circle = π x 6 ²÷ 2 Area of semi-circle = 56.55cm² 56.55cm²

18. Calculate the area and perimeter of this compound shape: 8cm 12cm 96cm² 56.55cm² Area of semi-circle = π x r ² ÷ 2 Area of semi-circle = π x 4 ²÷ 2 Area of semi-circle = 25.13cm² 25.13cm²

19. Calculate the area and perimeter of this compound shape: 8cm 12cm 96cm² 56.55cm² Total area = 96 + 56.55 + 25.13 = 177.68cm ² 25.13cm²