The answers are a) 43.96 cm, b) 351.68 cm, c) 28.8 cm and d) 307.72 mm
The formula to calculate the circumference of a circle is C= π d, or C = π 2r, where d is the diameter and r is radius.
A - C=3.14 x 2 x 7 = 43.96 cm
B - C=3.14 x 2 x 56 = 351.68 cm
C - C=3.14 x 9.2 = 28.8 cm
D - C=3.14 x 98 = 307.72 mm