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...eld emerged in the [[Hellenistic period|Hellenistic world]] during the 3rd century BC from applications of [[geometry]] to [[Astronomy|astronomical studies]]. [[Sumer]]ian astronomers studied angle measure, using a division of circles into 360 degrees.<ref>{{ ...

...r designed by a commission assembled by Pope Gregory XIII in the sixteenth century."}}{{efn|Many countries that use other calendars for religious purposes use ...ays; when Russia and Greece did so (for their civil calendars) in the 20th century, the jump was 13 days. For other countries and territories, see [[List of a ...

...peared throughout history, including the work of [[Desargues]] in the 17th century, all the way back to the implicit use of [[spherical geometry]] to understa ...the theory of [[manifold]]s and [[Riemannian geometry]]. Later in the 19th century, it appeared that geometries without the [[parallel postulate]] ([[non-Eucl ...