Spherical wedge (Volume)
A spherical wedge or ungula is a portion of a ball bounded by two plane semidisks and a spherical lune (termed the wedge’s base). The angle between
Lead is the axial advance of a helix or screw during one complete turn (360°). The lead for a screw thread is the axial travel for a single revolution.
The Archimedean spiral is the locus of points corresponding to the locations over time of a point moving away from a fixed point with a constant speed