KnowraHyperbolic triangleLinked fromLinked fromThe 3 pages that link to Hyperbolic triangle, each with the reason it gives.All 3Broader topic 2Compared with 1Nikolai LobachevskyBroader topic: Its angle sum is less than two right angles, a signature of Lobachevskian geometry.Hjelmslev's theoremBroader topic: The theorem applies to these triangles, whose angle data determine their congruence.