## 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 | |||||

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