It’s the same for all circles! The Circumference of a Circle
Find the circumference of the following circles. C = d C = 2 r 8 cm cm 2 C = d C= x 8 C = 25.1 cm (1 dp) C = d C= x 9.5 C = 29.8 cm (1 dp)
C = 2 r C = 2 x x 3 C = 18.8 mm (1 dp) C = 2 r C = 2 x x 2.1 C = 13.2 m (1 dp) The Circumference of a Circle Find the circumference of the following circles. C = d C = 2 r 3 mm m 3
23 cm 7.5 cm Find the circumference of the tyre and steering wheel. C = d C= x 23 C = 72.3 cm (1 dp) C = 2 r C = 2 x x 7.5 C = 47.1 cm (1 dp)
The Circumference of a Circle Find the perimeter of the following semi-circles. C = d C = 2 r 8 cm cm 2 Perimeter = ½ d + d = ½ x x = 20.6 cm (1 dp) Perimeter = ½ d + d = ½ x x = 24.4 cm (1 dp)
Perimeter = ¼ ( 2 r) + 2r = ¼ x 2 x x x 6 = 21.4 cm (1 dp) Perimeter = ¾(2 r) + 2r = ¾ x 2 x x x 8.5 = 57.1 cm (1 dp) The Circumference of a Circle Find the perimeter of the ¼ and ¾ circles. C = d C = 2 r cm 8.5 cm
The Circumference of a Circle Find the diameter/radius of the following circles. C = d C = 2 r C = 25 cm find the diameter. 5 6 d = 25 d = 25/ d = 8.0 cm (1 dp) 2 r = 30 r = 30/(2 ) r = 4.8 cm (1 dp) C = 30 cm find the radius.