A drill bit
based on the shape below,
a Reuleaux triangle,
cuts a square hole.
The base of a Pepto-Bismol
bottle is a Reuleaux
There is a Canadian coin
that is basically the shape of a Reuleaux
of constant width were studied by the Swiss
mathematician, Leonhard Euler
Reuleaux triangles were
named for Franz Reuleaux
(1829-1905), a German engineer,
mathematician and high school teacher.
Though he never had a driver's license, Felix
Wankel (1902-1988) developed the idea of a
rotary engine for
an automobile in the early 1920's. Wankel's design is
based on a Reuleaux triangle.
Triangular manhole covers
are used in some places in Minnesota.