What is the equation to get circumference of a circle if you have the diameter?
Circumference = Pi x Diameter
(Pi equals 3.14)
A wheel is in the shape of a circle. The formula for the circumference of a circle is 2πr where r is the radius. But, the diameter of a circle is twice the radius so this equation can be written, Circumference = πd where d is the diameter. The Circumference is therefore π times as big as the diameter, π = 3.142 or 22/7 approx.