EntityQ1332450· pop 32· linked from 150 articleselliptic geometrySign in to savenon-Euclidean geometryConnectionsparallelogramEntityspherical trigonometryEntityHarold Scott MacDonald CoxeterEntity3-sphereEntityRené DescartesEntityArchimedesEntitygeometryEntityPythagorasEntityEuclidEntityCarl Friedrich GaussEntityBlaise PascalEntityLeonhard EulerEntityJohannes KeplerEntitytriangleEntityareaEntityInternational Standard Book NumberEntityOmar KhayyámEntityDavid HilbertEntitycircleEntityangleEntityCategoriesClassical geometryMetric geometryNon-Euclidean geometry