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
Savilian Professor of Geometry world, saying that the professor of geometry should teach Euclid's "Elements", Apollonius's "Conics", and the works of Archimedes; tuition in trigonometry was to be shared by the two professors. As many students would have had little mathematical knowledge, the professors were also permitted to provide instruction in basic mathematics in English (as opposed to Latin, the language used in education at Oxford at the time). Savile's first choice for the professorship of geometry was Edmund Gunter, Professor of Astronomy at Gresham College, London. It was reported that Gunter demonstrated the use of his sector and quadrant, but Savile regarded this