We will discuss the Area and Perimeter of a Circle . The area (A) of a circle (or circular region) is given by. A = πr 2. where r is the radius and, by definition, π = \ (\frac {\textrm {Circumference}} {Diameter}\) = \ (\frac {22} {7}\) (Approximately). Define Circle Formulas Circle formulae are basic formulas of circles in geometry. The formula for calculating a circle 's circumference , or perimeter , is C = πd or C = 2πr, where "d" is the diameter and "r" is the radius. The formula A = πr2 represents the area of a circle , which is the region contained by its circumference . "r" is the radius. The correct way to find the perimeter of a circle is to calculate it using the formula C = 2π × r . If the diameter or radius of a circle is known circumference of the circle can be easily calculated. The ratio of Circumference to the Diameter of a circle is always a constant and that is π. How to Find the Perimeter of a Circle The perimeter of a circle is called the circumference . The formula for perimeter of a circle is the circumference formula. It is given as: C = 2πr or: C = πd Where C is the circumference , r is the radius of the circle , and d is the diameter of the circle . Here is an example of using this formula to find circumference of a circle with a radius of 3: C = 2π (3) = 6π, circumference = 6π.
