1. radius r = 20 cm
area = pi*r^2 = 3,14*400 = 1256 cm^2
circumference = 2pir = 2*3,14*20 = 136 cm
2. radius = 8 cm
area = 3,14*8^2 = 3,14*64 = 200,96 cm^2
circumference = 2*3,14*8 = 50,24 cm
3. radius = 1 cm
area = 3,14*1^2 = 3,14*1 = 3,14 cm^2
circumference = 2pir = 2*3,14*1 = 6,28 cm
hope these will help you