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# what is a circle in math?

what is a circle in math? Define its parts in detail. A circle is a locus of points whose distance is constant from some fixed point O. That fixed point is called the center of the circle and the fixed distance is called the **radius of the circle**. The locus of points is called the **circumference of circle. **

Here OA is called the radius of the circle. All radii of a circle are fixed in length so mOA=mOB.

## What are the basic terminologies of a circle?

### Circumference:

The circumference of a circle has value equal to 2πr where π is the ratio of circumference and diameter (d=2r) of the circle.

### Arc of a circle:

Any portion of circumference of a circle is known as the arc. AEB in the following figure shows the arc.

### Chord of a circle

Any line segment whose end points lie at the boundary of the circle is called **chord** and any **chord **passing through the circle is called the **diameter **of the circle. So a diameter bisects the circle.

### What is the segment of a circle?

A segment of a circle is the portion that is composed of an arc and the chord. The following figure shows how a chord and an arc divides a circle into its major segment and minor segment. Here AMB is the **major segment **and ASB is the **minor segment. **

### Sector of the circle

Sector of a circle is composed of two radii and the arc of the circle. Any two radii divides the circle into two sectors: **major sector** (pink shaded) and **minor sector (shaded orange) **as shown in the figure below.

### What is the area of a circle?

The area of a circle has the formula of π(r^2).

Also read here:

https://www.mathsisfun.com/geometry/circle-theorems.html

https://eevibes.com/how-to-test-if-a-function-is-even-or-odd/