Sphere     A three-dimensional figure with all of its points equidistant from its center.
Radius: r      Diameter: d      Surface area: S      Volume: V           S = 4 Pi r2 = Pi d2           V = (4 Pi/3)r3 = (Pi/6)d3
Sector of a Sphere      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 Pi rh           V = (2 Pi/3)r2h
Spherical Cap     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.
Radius of sphere: r      Radius of base: r1      Height: h      Surface area: S      Volume: V           r = (h2+r12)/(2h)           S = 2 Pi rh           V = (Pi/6)(3r12+h2)h
Segment and Zone of a Sphere     Segment: the portion of a sphere cut off by two parallel planes.     Zone: the curved surface of a spherical segment.
Radius of sphere: r      Radii of bases: r1, r2      Height: h      Surface area: S      Volume: V           S = 2 Pi rh           V = (Pi/6)(3r12+3r22+h2)h
Lune of a Sphere     The curved surface of the intersection of two hemispheres.
Radius: r      Central dihedral angle: theta (in radians),           alpha (in degrees)      Surface area: S      Volume enclosed by the lune           and the two planes: V           S = 2r2theta = (Pi/90)r2alpha           V = (2/3)r3theta = (Pi/270)r3alpha
For more about spheres, visit: Ask Dr. Math: Volume of a Sphere Volume of a Hemisphere Using Cavalieri's Theorem Volume of a Spherical Cap The Geometry Center: Spheres Eric Weisstein's World of Mathematics: Sphere

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