1. Area & Perimeter Circumference of a Circle Grade 3

2. The circumference of a circle is the circle’s perimeter. It is given by the following formula… C = Circumference π = ‘pi’ = 3.14…… (on calculator) d = diameter of the circle Circumference of a Circle C = πd

3. C = π x 9cm C = 28.27cm (2dp) Circumference of a Circle A circle has a diameter of 9cm. Calculate its circumference.

4. C = πd C = π x 12cm C = 37.70cm (2dp) Circumference of a Circle A circle has a radius of 6cm. Calculate its circumference

5. C = πd C = π x 16m C = 50.27m (2dp) 50.27 ÷ 2 = 25.13m Add on the straight line!  25.13 + 16m  41.13m Circumference of a Circle Calculate the Perimeter of this semicircle.

6. Circumference of a Circle

7. 50cm C = πd C = π x 50 C = 157.08 cm C = 1.5708 m C = 1570.8 m d = 50cm Convert into metres (÷ 100) x 1000 Circumference of a Circle This is a car tyre for a Mini Cooper. Its Diameter is roughly 50cm. If the wheel has spun round 1000 times, how far has the car travelled? (in metres)

8. 50cm We need to divide the distance travelled by the Circumference of the wheel…  Make sure the units are the same first! C = 1.5708 m (from before…) 15,000 km 15,000,000 m x 1000 (to change to metres) 15,000,000 ÷ 1.5708 = 9,549,274 times! Circumference of a Circle This is a car tyre for a Mini Cooper. The Mini has travelled 15,000km in total since being built. How many times has the wheel turned?