Spherical geometry other geometric concepts are defined as in plane geometry, but with straight lines replaced by great circles. Thus, in spherical geometry, angles are defined between great circles, resulting in a spherical trigonometry that differs from ordinary trigonometry in many respects; for example, the sum of the interior angles of a triangle exceeds 180 degrees. Spherical geometry is "not" elliptic geometry, but is rather a "subset" of elliptic geometry. For example, it shares with that geometry the property that a line has no parallels through a given point. Contrast this with Euclidean geometry, in which a line has one parallel through
How many angels can dance on the head of a pin? Suite Part II: Let It Grow", a song from the 1973 Grateful Dead album Wake of the Flood, includes the line "As well to count the angels dancing on a pin." In the comic book "The Crow" by James O'Barr, the main character asks this question to one of his victims before killing them, answering himself, "Depends on the tune". The song "Velodrome" from Minnesota rapper Dessa's 2018 album Chime, references this question in the first verse asking, "Aquinas, call on me/ How many angels on the/ Head of your pin?" How many angels can dance on the head of