# What the formula to find the perimeter of a circle

It can be shown rigorously that the difference in the "inner" and "outer" polygonal areas shrinks to zero, telling us that both sequences of polygonal areas have the same limit. Therefore, they require a special formula to determine perimeter. Remember the old adageâ€”measure twice, cut once.

Given the radius of a circle, the circumference or perimeter can be calculated using the formula bwloe: If we know the diameter. If we know the diameter of a circle, the circumference can be found using the formula.

If we know the area. If we know the area of a circle, the circumference can be found using the formula: A circular flower-bed has a radius of 9 m.

Examples of Perimeter of a Circle Back to Top. Central Angle of a Circle Formula.

Formula for Perimeter of a Polygon. Formula for Perimeter of a Rectangle.

Formula for Perimeter of a Square. Formula for Perimeter of a Triangle.

### Circle, Its Perimeter and Area

It is calculated using the formula Pi x diameter, or 3. Pi is the result of dividing a circle's circumference by its diameter.

No matter the length of the circumference or diameter, Pi is always the same. It is a number that goes on infinitely: To make it easier to use, it is shortened to 3.

It is usually represented by the pictured symbol, which is the Greek letter of Pi. Review the meaning of diameter. Diameter is the distance of a straight line, drawn through the midpoint of a circle, that connects both sides of the circle.

It is represented in the generic formula as d. Brush up on radius.

## Perimeter of a Circle Formula

The radius is equivalent to half the length of the diameter. How do I find the radius when I get the circumference? The diameter is just the radius times two, so divide the diameter by two and you will have the radius of the circle!

Not Helpful 41 Helpful What is the formula used to calculate diameter? Diameter is just simply 2 times the radius.

The circumference is diameter x pie OR 2 x radius x pie. Not Helpful 81 Helpful How do I find the area of a circle when only given the circumference?

Divide the circumference by pi. Square the radius, and multiply by pi.

### How to Find the Perimeter of a Circle

Not Helpful 20 Helpful How can I find the diameter of the circle, once I know the circumference? To get the diameter of a circle take the circumference C and divide it by pi 3. Not Helpful 45 Helpful What is the answer of the circumference of a circle? The answer depends on your number. For example, pie or 3.