Do now: Work out the circumferences and areas of these circles 10 cm 12 cm 9 cm 2 cm 1.5 cm
How well did you do? 10 cm 12 cm 9 cm 2 cm 1.5 cm C = 31.4 cm C = 56.5 cm C = 37.7 cm C = 9.4 cm C = 6.3 cm
How well did you do? 12 cm 9 cm 2 cm 1.5 cm A= π × 5 2 A = 78.5 cm 2 5 cm A= π × 6 2 A = cm 2 A= π × 1 2 A = 3.1 cm 2 A= π × 9 2 A = cm 2 A= π × A = 7.1 cm 2
Circumference = π × diameter C=πd OR Circumference = 2 × π × radius C=2πr Area = π × radius × radius A=πr 2 Did you remember these important formulae? You are expected to remember these in your GCSE exam. diameter radius