A circle is a series of equidistant points from one point, which, in turn, is the center of this circle. The circle also has a radius equal to the distance of these points from the center.

The ratio of the length of a circle to its diameter is the same for all circles. This relation is a number, which is a mathematical constant, which is denoted by the Greek letter *π*.

Determination of the circumference

You can calculate the circle using the following formula:

*r* - circle radius

*D* - circle diameter

*L* - circumference

**Calculate circumference**having a radius of 10 centimeters.

**Formula for calculating the dyne of a circle** has the form:

where L is the circumference, π is 3.14, r is the radius of the circle, D is the diameter of the circle.

Thus, a circumference having a radius of 10 centimeters is equal to:

L = 2 × 3.14 × 5 = 31.4 centimeters

*Circle* represents a geometric figure, which is the set of all points on the plane remote from a given point, which is called its center, for a certain distance, not equal to zero and called the radius. Scientists knew how to determine its length with varying degrees of accuracy in ancient times: science historians believe that the first formula for calculating the circumference was drawn up around 1900 BC in ancient Babylon.

With geometric shapes such as circles, we come across daily and everywhere. It is its shape that the outer surface of the wheels that various vehicles are equipped with. This detail, despite its outward simplicity and unpretentiousness, is considered one of the greatest inventions of mankind, and it is interesting that the aborigines of Australia and the American Indians until the arrival of Europeans had absolutely no idea what it was.

In all likelihood, the very first wheels were pieces of logs that were mounted on an axle. Gradually, the design of the wheel improved, their design became more and more complex, and for their manufacture it was required to use a lot of different tools. First, wheels appeared, consisting of a wooden rim and spokes, and then, in order to reduce the wear of their outer surface, they began to uplift it with metal stripes. In order to determine the lengths of these elements, it is also required to use the formula for calculating the circumference (although in practice, most likely, the masters did this “by eye” or simply gird the wheel with a strip and cut off its required section).

It should be noted that *wheel* It is used not only in vehicles. For example, a potter’s wheel has its shape, as well as elements of gears of gears, which are widely used in technology. Since ancient times, wheels have been used in the construction of watermills (the oldest known structures of this kind by scientists were built in Mesopotamia), as well as spinning wheels used to make yarn from animal wool and plant fibers.

*Circle* Often can be found in construction. Their shape is quite widespread round windows, very characteristic of the Romanesque architectural style. The manufacture of these structures is a very difficult matter and requires high skill, as well as the availability of special tools. One of the varieties of round windows are portholes installed in ships and aircraft.

Thus, to solve the problem of determining the circumference is often necessary to design engineers who develop various machines, mechanisms and assemblies, as well as architects and designers. Since the number *π*Since the necessary for this is infinite, it is not possible to determine this parameter with absolute accuracy, and therefore, its degree is taken into account in the calculations, which is necessary and sufficient in a particular case.

### Entering data in a calculator for calculating the circumference of a circle

You can enter numbers or fractions in the online calculator. Read more in the rules for entering numbers.

**N.B.** In the online calculator, you can use the values in the same unit of measure!

If you have difficulty converting units, use the unit of distance and length converter.

### Formulas for calculating the circumference.

- P = 2 π r
- P = π d

where P is the circumference,

r is the radius of the circle,

d is the diameter of the circle,

π = 3.141592.

You can enter numbers or fractions (-2.4, 5/7,.). Read more in the rules for entering numbers.

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My name is Dovzhik Mikhail Viktorovich. I am the owner and author of this site, I have written all the theoretical material, and also developed online exercises and calculators that you can use to study mathematics.