Arbelos

An arbelos is a special shape that is made up of three semicircles that share the same diameter and all have the same center point. It is shaped like a crescent moon, with two equal curved sides and a flat bottom. The three semicircles fit together perfectly to form an arbelos, which looks like a big sombrero. It is named after the Greek word for a crescent shape. The shape of an arbelos is used quite often in mathematics and is especially useful in calculating the area and perimeter of a circle. It is also used to prove certain theorems or equations.