To find the diameter, find the circumference, i.e the length covered in one revolution, and then subject the diameter from formulas.
Circumference = 3.6 ÷ 18 = 0.2m = 2πr
πr = 0.2 ÷ 2 = 0.1
r = 0.1 ÷ (22/7) = (0.1 * 7) ÷ 22 = 0.7 ÷ 22
r = 0.0318
Diameter = 2r
Diameter = 2 * 0.0318 = 0.0636m ...//Ans ...
