What is the formula of PERIMETER OF CIRCLE ?

Dear Student,.. the perimeter of a circle has its own special name, called "circumference." The symbol is a capital C. It is calculated using the formula Pi x diameter, or 3.14 x d = C. It can also be calculated by Pi x (2 x radius) = C or 3.14 x (2 x r) = C. [C=2πr] .... Regards.