## Diameter of a circle. What is the radius, chord and circumference of a circle?

The diameter, i.e. the segment connecting two points of the edge of the circle (circle), passes through the center of the circle (circle). What is the radius and circumference of a circle? How should the circumference of a circle be calculated?

## 1. Diameter - what is it?

According to the definition, the diameter of a circle or circle is a line segment connecting two points of the edge of the circle (circle) that pass through the center of the circle (circle).

## 2. Diameter of the circle

A circle is a geometric figure defined by the center of the circle (fixed point on the plane) and the radius of the circle (given distance in the same plane).

A circle may be considered to be the set of all points in a given plane whose distance from the center is less than or equal to the radius.

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The radius is the distance between the center of the circle and any point on the edge of the circle. There are an infinite number of rays in one circle that extend in all directions from the center.

Each of these rays is of equal length. If the radius is extended so that it touches the opposite circle, the diameter will be created.

## 4. Diameter and chord of a circle

A chord of a circle is a line segment that connects any two of its points. Within one circle there can be an infinite number of chords of the same or completely different length. One of the special cases of a chord is the diameter.

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## 5. Diameter and circumference

The circumference of a circle is the length of its circle, and the circle is actually the edge of the circle. To imagine it even better, it can be said that the circumference of the circle gathers all the points lying at the same distance from the center (their distance is equal to the radius). The center of the circle does not belong to the circle.

As in the case of a circle, there are three types of segments inside a circle (where only their ends are included in the circle). This is the radius, chord and diameter.

## 6. Circle diameter - pattern

The circumference formula of the circle is also the circumference formula using the radius and is as follows:

l = 2⋅π⋅r

l - indicates the circumference of the circle or the length of the circle π ≈ 3.14 - is a constant irrational number r - radius of the circle

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Knowing that the two rays together have the same length as the diameter, we can use the second formula.

The formula for the circumference of a circle using the diameter:

L = d⋅π

d - diameter of the circle

The formula for the area of ​​a circle with a given radius:

P = π⋅r²

By the way, the formula describing the number Pi (π).

π = ld

l - the circumference of the circle or the length of the circle d - diameter of the circle

## 7. Diameter - tangent and incisal

When talking about a circle, there are two types of lines: tangent and secant. A tangent is a line that has exactly one point in common with the circle. The second straight line - called the secant, has two points in common with the circle.

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