Properties

• Angular sector In a plane, a geometric figure defined by the union or the intersection of two half-planes whose boundaries intersect at a point O called the vertex of the angular sector.
  
• Circular sector The portion of a circle between two radii. The area of a circular sector that corresponds to an angle of [latex]α[/latex]° in a circle of radius [latex]r[/latex] has the relationship : [latex]A=\dfrac {α} {360}\pi r^{2}[/latex]

• Spherical sector If the radius of a sphere revolves around the boundary of a small circle of the sphere, it forms a conical surface and divides the sphere into two spherical sectors, one salient, the other re-entrant. The term "spherical sector" usually refers to the salient sector. This sector can be described as the union of a spherical cap and a cone whose vertex is at the centre of the sphere and whose base corresponds to the base of the spherical cap. The volume of a spherical sector that corresponds to a spherical cap of height [latex]h[/latex] in a sphere of radius [latex]r[/latex] has the relationship : [latex]V=\dfrac {2 \pi r^{2} h} {3}[/latex]