Arbelos - the Shoemaker's Knife
The
shaded area in the figure below is called arbelos (Greek for shoemaker's knife)
because it resembles the blade of a knife
used by ancient cobblers. An
arbelos is constructed by three semicircles
where the position of their central notch is arbitrary and can be
located
anywhere along the diameter of the outer semicircle.
- Drag the red point along the diameter to change the shape
of the arbelos.
- Construct an arbelos with ruler and compass on paper.
- Construct a dynamic arbelos like the one above with an
interactive geometry software (e.g. GeoGebra).
- Find out about interesting properties of the Arbelos on the Internet.