1. The Circle

2. The language of circles Circumference: The distance round the circle Circumference: The distance round the circle Diameter: the distance from one point on the circumference to another point passing through the centre Diameter: the distance from one point on the circumference to another point passing through the centre Radius: the distance from the centre to the circumference Radius: the distance from the centre to the circumference

3. Formulae of circles Area: A = π r 2 Area: A = π r 2 Circumference: C = π D Circumference: C = π D π = 3.14 OR π on your calculator π = 3.14 OR π on your calculator You must learn these facts!!!

4. Calculating the circumference 12 cm 15 cm πd C = πd C = π x 12 = 37.68 cm π d C= π d C = π x 15 = 47.1 cm

5. Calculating Circumferences 4cm Radius = 4 cm so diameter = 2 x 4 = 8 cm C = πd C= π x 8 = 25.04 cm REMEMBER: The radius is half of the diameter

6. Calculating areas 12 cm 20 cm D = 12 cm D = 20 cm R = 6 cm r = 10 cm A = πr 2 A = π r 2 A = π x 6 x 6 = 113.1 cm 2 A = π x 10 x 10 = 314 cm 2