EntityQ332430· pop 26· linked from 53 articlesabsolute geometrySign in to savegeometry without the parallel postulateConnectionsparallelogramEntityEuclidean geometryEntityaxiomatic systemEntityRené DescartesEntityArchimedesEntitygeometryEntityPythagorasEntityEuclidEntityCarl Friedrich GaussEntityBlaise PascalEntityLeonhard EulerEntitytriangleEntityareaEntityInternational Standard Book NumberEntityOmar KhayyámEntityDavid HilbertEntitycircleEntityangleEntitysquareEntityPythagorean theoremEntityCategoriesClassical geometry