secteur

Secteur is a French noun meaning a part or division of something. The term has several related but distinct uses in mathematics, economics, and urban planning.

In mathematics, the sector of a circle is the region enclosed by two radii and the arc between them. The central angle is the angle between the radii. If the circle has radius r and the central angle is θ radians, the area of the sector is A = (1/2) r^2 θ and the arc length is s = r θ. When θ is given in degrees, the area is A = (θ/360) π r^2 and the arc length is s = (θ/360) 2π r.

In economics and social science, a sector denotes a distinct part of an economy or activity, such as the primary sector (extraction and agriculture), the secondary sector (manufacturing), and the tertiary sector (services). The term is used to classify industries and to analyze economic structure. It also appears in policy and planning contexts, for example in references to the private sector (secteur privé) and the public sector (secteur public).

In urban planning and geography, secteur can refer to a geographic or administrative subdivision of a city or municipality, defined for planning, governance, or statistical purposes. The exact boundaries and naming conventions of sectors vary by country and local administration.

Etymology and usage: secteur comes from Latin sectus, meaning cut or divided, via Old French secteur. It is cognate with the English word sector and used similarly in French-speaking contexts to denote a part of a whole.