Here is the link.
keywords:
[Mathematics]
[Geometry]
[Trigonometry]
[sin(x) / x]
[sin x / x]
[limit is 1]
[limit is unity]
[fundamental inequality]
[inequalities]

A Reuleaux triangle is a curve of constant width other than a circle.
Here is the link to the Wikipedia article on this topic.
keywords:
[Mathematics]
[Geometry]
[counter-intuitive results]
[counterintuitive results]
[arc of a circle]
[equilateral triangle]