EntityQ45926· pop 37· linked from 332 articlesannulusSign in to savegeometric surface defined by two concentric circlesConnectionsMöbius stripEntitymathematicsEntityLatinEntityInternational Standard Book NumberEntitycircleEntitysolar eclipseEntityPythagorean theoremEntitycalculusEntitysphereEntitypointEntitycylinderEntityintegralEntityellipseEntityline segmentEntitysurfaceEntitytorusEntitycomplex analysisEntitydiskEntitytangentEntitychordEntityCategoriesCirclesElementary geometryGeometric shapesPlanar surfaces