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
Environmental Seismic Intensity scale or lower, the ESI 2007 scale is intended to be used as a supplement to other intensity scales. a) the Definition of intensity degrees on the basis of Earthquake Environmental Effects; b) the Guidelines, which aim at better clarifying i) the background of the scale and the scientific concepts that support the introduction of such a new macroseismic scale; ii) the procedure to use the scale alone or integrated with damage-based, traditional scales; iii) how the scale is organized; iv) the descriptions of diagnostic features required for intensity assessment, and the meaning of idioms, colors, and fonts. Since 2007, the