1. 1 of 84 SHAPE AND SPACE Circles

2. 2 of 84 The circumference of a circle Use π = 3.14 to find the circumference of this circle. C = πd 8 cm = 3.14 × 8 = 25.12 cm

3. 3 of 84 The circumference of a circle Use π = 3.14 to find the circumference of the following circles : C = πd 4 cm = 3.14 × 4 = 12.56 cm C = 2 πr 9 m = 2 × 3.14 × 9 = 56.52 m C = πd 23 mm = 3.14 × 23 = 72.22 mm C = 2 πr 58 cm = 2 × 3.14 × 58 = 364.24 cm

4. 4 of 84 Formula for the area of a circle We can find the area of a circle using the formula radius Area of a circle = πr 2 Area of a circle = π × r × r or

5. 5 of 84 The circumference of a circle Use π = 3.14 to find the area of this circle. A = πr 2 4 cm= 3.14 × 4 × 4 = 50.24 cm 2

6. 6 of 84 The area of a circle Use π = 3.14 to find the area of the following circles: A = πr 2 2 cm = 3.14 × 2 2 = 12.56 cm 2 A = πr 2 10 m = 3.14 × 5 2 = 78.5 m 2 A = πr 2 23 mm = 3.14 × 23 2 = 1661.06 mm 2 A = πr 2 78 cm = 3.14 × 39 2 = 4775.94 cm 2

7. 7 of 84 Practice Time!

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