Back حلقة (هندسة رياضية) Arabic চাকতি (গণিত) Bengali/Bangla Corona circular Catalan Mezikruží Czech Ункă (геометри) CV Annulus (matematik) Danish Kreisring German Δακτύλιος (μαθηματικά) Greek Ringo (geometrio) Esperanto Corona circular Spanish
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In mathematics, an annulus (pl.: annuli or annuluses) is the region between two concentric circles. Informally, it is shaped like a ring or a hardware washer. The word "annulus" is borrowed from the Latin word anulus or annulus meaning 'little ring'. The adjectival form is annular (as in annular eclipse).
The open annulus is topologically equivalent to both the open cylinder S1 × (0,1) and the punctured plane.
- ^ Haunsperger, Deanna; Kennedy, Stephen (2006). The Edge of the Universe: Celebrating Ten Years of Math Horizons. ISBN 9780883855553. Retrieved 9 May 2017.