Circles

​Sector of a Circle

The portion (or part) of the circular region enclosed by two radii and the corresponding arc is called a sector of the circle.

​Sector of a Circle

Note:

• The region OAXB is a sector of the circle with centre O. Angle AOB is called the angle of the sector.

• The region OAYB is also a sector of the circle. OAXB is called the minor sector and OAYB is called the major sector.

• Angle of the major sector is 360° – Angle AOB.

Segment of a Circle

The portion (or part) of the circular region enclosed between a chord and the corresponding arc is called a segment of the circle.

Segment of a Circle

• AB is a chord of the circle with centre O. Region ACB is a segment of the circle.

• Also note that region ADB is another segment of the circle formed by the chord AB.

• ACB is called the minor segment and ADB is called the major segment.

Area of a circle