In circle math the terms related to the circle are discussed here.

A circle is such a closed curve whose every point is equidistant from a fixed point called its center.

**The symbol of circle is O**.

What are the terms related to the circle?

The terms related to the circle math are:

**(i) Center:**

The *center* of a circle is a fixed point within the circle from which all the points of the closing curve are equidistant.

**O** is the centre.

**(ii) Circumference: **

The curve which closes a circle is called its circumference. The length of the *circumference* is called the length of the circle.

**(iii) Radius: **

The distance from the centre to any point on the circumference of a circle is called the *radius* of the circle. The symbol of the radius is ** r**.

**(iv) Diameter: **

The line-segment
passing through the centre and meeting the points on the circumference
is called the diameter of the circle. Diameter is denoted by '** D**'.

** AB** is a diameter of the circle.

** Diameter is twice the length of the radius concerned**.

Thus, **D = 2r** [**Diameter = 2radius**]

or

**r = ****D/2** [**Radius = ****Diameter/2**]

**(v) Arc: **

Any part of the circumference is called an arc of the circle.

**(vi) Chord: **

The line-segment joining the two ends of an arc is known as a chord. A diameter is the longest chord of a circle.

Here,

**O** is the *centre.*

**OP** is one *radius.*

**AB** is a *diameter.*

**MN** is a *chord .* (**line-segment**)

**OA** and OB are also *radii.*

**Related Concepts on ****Geometry - Simple Shapes & Circle**

**● Polygon**

**● Angle**

**● Triangle**

**4th Grade Math Activities
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