Perimeter of a deltoid


In geometry, a deltoid, also known as a tricuspoid or Steiner curve, is a hypocycloid of three cusps. In other words, it is the roulette created by a point on the circumference of a circle as it rolls without slipping along the inside of a circle with three times its radius. The perimeter (total arc length) of the deltoid is 16 times the radius of the rolling circle.

Related formulas


PPerimeter of the deltoid (m)
aThe radius of the rolling circle (m)