## What is a Circle?

In geometry, a circle **is the area or surface contained within a circumference**. The word comes from the Latin *circŭlus* , diminutive of the Latin word *circus* , which means ‘fence’.

In a generic way, the word circle is also often used when several elements are placed forming a circular space, such as a circle. For example: “The players made a circle to talk.”

At a social level it is also identified as **a club, a casino or a society that meets for different purposes that can be recreational or artistic**. For example: a circle of readers, the Vienna Circle. Also called the place where its members meet.

In this sense, the words athenaeum and center can sometimes be used as synonyms. For example: the circle of Fine Arts.

Normally used in the plural, circles also **refers to a group of people who belong to a certain environment or sector of society**. For example: “Aristocratic circles”.

Some synonyms, depending on the context in which they are applied, can be circumference, perimeter, contour, ring, disk, orbit, roundabout, fence, contour, club, casino, athenaeum.

## Polar Circle

The polar circle is called the parallel that is found both in the north and in the south of the planet at a latitude 66 ° 33 ’46 ”, being that the north polar circle is known by the name of Arctic and the south polar circle by the name from Antarctic.

Polar circles are characterized by having at least one day in the year in summer when the sun never sets, and one day in the year in winter when the sun never rises.

## Color circle

Color circle is the ordered and circular representation of colors (both primary and derivatives) based on their tone. In the color wheel, the colors can be staggered or in gradient. They can be composed of different amounts of colors, which will vary from six to forty-eight.

## Circle and circumference

In geometry, a distinction is made between circle and circumference, with the circle being the surface and the circumference being the curved line that delimits it.

However, on many occasions the word circle is used interchangeably. For example, it is often said that a group of people surrounding the same distance from an object located in the center are “in a circle” and not “in a circle”.

## Circle area

The area of a circle is the surface it occupies. To find it, it is common to use the following formula: A = π • r², where π is the number pi, used in many cases as 3.1416 and *r* the radius of the circle.

## Circle perimeter

The perimeter of a circle corresponds to the circumference. To calculate the perimeter, this formula P = d • π can be used, *d* corresponding to the value of the diameter of the circumference.

## Squaring the circle

In mathematics, squaring the circle is a problem that has been tried to solve since Ancient Greece and has no solution by geometric methods. It consists of calculating only with a ruler and a compass the dimensions of a square whose area is equivalent to that of a given circle.

The square of the circle is spoken of colloquially to refer to an impossible problem to solve. For example: “Forget it, that’s like looking for the square of the circle.”