Parts of a circle is the name associated with a line consisting of sets of points in a plane on a circle. Any circular objects such as coins, the moon, the sun, etc have been described by many as a circle. In a layman’s perception, any circular object is seen as a circle. A circle is a line consisting of all sets of points that are equidistant from a fixed point called the center. On this page, we will discuss parts of a circle.

Parts of a Circle

The basic composition of a circle has its specific name and they are named as follows;

• Radius

• Diameter

• circumference

• chord

• Arc

• Sector

• segment

• Center

**Circumference**: a line that bounds a circular object or spherical surface. Now, taking a circle, for instance, the circumference of a circle is the line that bounds the circle.

**An arc**: This refers to any part on the circumference of the circle. The distance PQ along the circumference of the circle in the figure below is the arc.

**Chord**: any straight line that joins one part of the circumference to another part of the circumference is called the chord. The line AB in the figure below is the chord.

**Diameter**: any chord that passes through the center of the circle is called the diameter. All diameters are special chords but not all chords are diameters. Thus the chord AB in the figure below is a diameter.

**Radius**: any line from the center of a circle to any point on the circumference is called the radius. The distance OE in the figure below is the radius of the circle.

**Segment**: chord divides the circle into two equal parts called segments. The area bounded by a chord is called a segment. The area bounded by CD is called the minor segment and the other part is called the major segment.

**sector**: The area bounded by two radius (radii) of the circle. In the figure below the region bounded by ∠OPQ is called the sector.