A three-dimensional figure with all of its points equidistant from its center.

 
     Radius: r
     Diameter: d
     Surface area: S
     Volume: V

          S = 4 p r² = Pi d²
          V = (4 p / 3) r³ = (p / 6) d³

     The part of a sphere between two right circular cones that have a common vertex
     at the center of the sphere, and a common axis. (The interior cone may have a base
     with zero radius.)

 
     Radius: r
     Height: h
     Volume: V

          S = 2 p r h
          V = (2 p / 3) r² h

    The portion of a sphere cut off by a plane. If the height, the radius of the sphere, and
    the radius of the base are equal: h = r (= r₁), the figure is called a hemisphere.

          r = (h²+r₁²) / (2h)
          S = 2 p r h
          V = (p / 6) (3 r₁² + h²) h

    Segment: the portion of a sphere cut off by two parallel planes.
    Zone: the curved surface of a spherical segment.
    

          S = 2 p r h
          V = (p / 6) (3r₁²+3r₂²+h²) h

    The curved surface of the intersection of two hemispheres.

          S = 2r²theta = (p/90)r²alpha
          V = (2/3)r³theta = (p/270)r³alpha