# Definition:Sector

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## Disambiguation

This page lists articles associated with the same title. If an internal link led you here, you may wish to change the link to point directly to the intended article.

**Sector** may refer to:

### Sector of Circle

A **sector of a circle** is the region bounded by two radii and an arc.

In the words of Euclid:

*A***sector of a circle**is the figure which, when an angle is constructed at the center of the circle, is contained by the straight lines containing the angle and the circumference cut off by them.

(*The Elements*: Book $\text{III}$: Definition $10$)

In the diagram below, $BAC$ is a **sector**.

### Spherical Sector

A **spherical sector** is a surface of revolution of a sector of a circle $C$ rotated $360 \degrees$ around a diameter of $C$.

The surfaces of the **spherical sector** are:

- the zone of $S$, formed by the arc of the sector
- one or two conical surfaces formed by the radius or radii of the sector

where $S$ is the sphere formed as the surface of revolution of $C$ as it rotates $360 \degrees$ around the same diameter of $C$.

## Also see

- Results about
**sectors**can be found**here**.