Explain the difference between a sector and a segment.

A sector and a segment are both parts of a circle, but they differ in their formation and shape.

1. A sector of a circle is the portion of the circle enclosed by two radii and their intercepted arc. It looks like a slice of a pie or pizza. The size of a sector is determined by the degree of the central angle.

2. A segment of a circle, on the other hand, is the area enclosed by a chord and the arc subtended by the chord. It looks like a section of the circle that has been 'cut off' by a straight line (the chord). The size of a segment is determined by the length of the chord and the size of the arc.

In summary, a sector is defined by two radii and an arc, while a segment is defined by a chord and an arc.