1) Geometric shape
Found on
https://www.crosswordclues.com/clue/arbelos
In geometry, an arbelos is a plane region bounded by a semicircle of diameter 1, connected at the corners to semicircles of diameters r and (1 − r), all rising above a common baseline. Archimedes is believed to be the first mathematician to study its mathematical properties, as it appears in propositions four through eight of his Book of Lemmas....
Found on
http://en.wikipedia.org/wiki/Arbelos
The figure bounded by three semicircles AB, BC, and AC, where ABC is a straight line. Archimedes (about 250 BC) called it an 'arbelos' – the Greek word for a knife of the same shape used by shoemakers to cut and trim leather – and wrote about it in his Liber assumptorum (Book of Lemmas)....
Found on
http://www.daviddarling.info/encyclopedia/A/arbelos.html
No exact match found.
