# What is the meaning of circles

## Circle - definition and characteristics

Reading time: 5 min

The circle is a flat geometric figure with an infinite number of points at the same distance from the center point and resulting in a circular line.

The area enclosed by the circular line is called the circular area. The distance to the center is called the radius.

If we were to extend the definition to a space, we would speak of a sphere.

If one already knows limit values, one can also define that the circle is a regular polygon that consists of an infinite number of sides. The following animation shows this:

### Features of the circle

• The circle has no corners, an infinite number of sides (the circular line) and 1 area.
• The circle has no interior angles.
• The circle is point-symmetrical to its origin.
• All lines from one point through the center point to the opposite point are of the same length (the diameters).
• A line from the center point to another point on the circle is called a radius. It is half the length of the diameter.
• A circle does not belong to the group of polygons (polygons).

### Circle illustration with formulas

Link to the graphic: https://www.matheretter.de/img/wiki/kreis-formeln.png

### Components of the circle

Further distances and areas result on the circle if you enter two radii (plural of radius) and create an angle:

We look at that Building the circle in the other articles to: