Relationship between the circumference of a circle and its diameter.

Expert Answers
embizze eNotes educator| Certified Educator

The formula for the circumference of a circle is pi*d, where pi is a constant (pi approximately 3.1415926) and d is the diameter of the circle.

Another formula for the circumference is C=2*pi*r where r is the radius of the circle. Note that the diameter is twice the length of the radius.


The quotient of the circumference and the diameter of a circle is the constant pi.



hkj1385 eNotes educator| Certified Educator

Circumference of the circle = 2*pi*r  ; where 'r' = radius of the circle

Now, radius of the circle 'r' = diameter of the circle/2

Thus, circumference of the circle = pi*d ; where 'd' = diameter of the circle