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. It can also be defined as a similar roulette where the radius of the outer circle is 3⁄2 times that of the rolling circle. It is named after the Greek letter delta which it resembles.
More broadly, a deltoid can refer to any closed figure with three vertices connected by curves that are concave to the exterior, making the interior points a non-convex set.
Other articles related to "deltoid curve, deltoids, deltoid":
... Deltoids arise in several fields of mathematics ... The set of complex eigenvalues of unistochastic matrices of order three forms a deltoid ... A cross-section of the set of unistochastic matrices of order three forms a deltoid ...
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