There are few different parts of a circle that are required for the exam. It is worth making some revision cards with a sketch and a definition for each of the following terms.

**Sector**

A sector is an area of the circle that is enclosed by two radii and an arc (see below for the definition of an arc). When we have a whole circle and it is split into two sectors, the larger one of the sectors is known as the major sector and the smaller sector is known as the minor sector.

In the exam, you may be given a sector and asked to work out what the area or perimeter of the sector is or what arc length is.

**Chord**

A chord is a straight line that goes from one side of the circle to the other side. There are two examples of a chord on the circle below.

A diameter is a special example of a chord that passes through the centre of a circle.

**Segment**

A Segment is the area that is enclosed by a chord and an arc. When we have a whole circle that is split into two segments, the larger of the segments is known as the major segment and the smaller segment is known as the minor segment (like the sector, the larger one is called major and the smaller one is called minor).

**Arc**

An arc is a part of the circumference of a circle and it does not matter how the arc comes about. The arc may come about because of a chord or a segment.

When a circle is split into two arcs, the longer arc will be known as the major arc and the shorter arc will be known as the minor arc.

**Tangent**

A tangent is a straight line that touches the edge of a circle. The circle below has two tangents.