Editing Arbelos (section)

{{Short description|Plane region bounded by three semicircles}}
[[File:Arbelos.svg|right|thumb|320px|An arbelos (grey region)]]
[[File:Arbelos sculpture Netherlands 1.jpg|thumb|Arbelos sculpture in [[Kaatsheuvel]], Netherlands]]

In [[geometry]], an '''arbelos''' is a plane region bounded by three [[semicircle]]s with three apexes such that each corner of each semicircle is shared with one of the others (connected), all on the same side of a [[straight line]] (the ''baseline'') that contains their [[diameter]]s.<ref name=wolfram/>

The earliest known reference to this figure is in [[Archimedes]]'s ''[[Book of Lemmas]]'', where some of its mathematical properties are stated as Propositions 4 through 8.<ref name=archBLprop4/> The word ''arbelos'' is Greek for 'shoemaker's knife'. The figure is closely related to the [[Pappus chain]].