A curve which can be turned continuously inside an equilateral triangle. There are an infinite number of delta curves, but the simplest are the circle and lens-shaped -biangle. All the curves of height have the same perimeter . Also, at each position of a curve turning in an equilateral triangle, the perpendiculars to the sides at the points of contact are concurrent at the instantaneous center of rotation.

# Delta Curve

## See also

Equilateral Triangle, Lens, Reuleaux Polygon, Reuleaux Triangle, Rotor## Explore with Wolfram|Alpha

## References

Honsberger, R.*Mathematical Gems I.*Washington, DC: Math. Assoc. Amer., pp. 56-59, 1973.

## Referenced on Wolfram|Alpha

Delta Curve## Cite this as:

Weisstein, Eric W. "Delta Curve." From
*MathWorld*--A Wolfram Web Resource. https://mathworld.wolfram.com/DeltaCurve.html