hyperbolic geometryOne of the two main types of non-Euclidean geometry and the first to be discovered. It is concerned with saddle-surfaces, which have negative curvature and on which the geodesics are hyperbolas. In hyperbolic geometry, contrary to the parallel postulate, there exists a line m and a point p not on m such that at least two distinct lines parallel to m pass through p. As a result: the sum of the angles of a triangle is less than 180° and, for a right triangle, the square of the hypotenuse is greater than the sum of the squares of the other two sides. Related entries elliptical geometry hyperbolic function Related categories GEOMETRY• SPACE AND TIME Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History |