For questions about osculating-circles, Descartes Theorem, Radius of Curvature, and evolutes.
An osculating circle is the circle tangent to a given curve at a given point and at infinitely close adjacent points. Consequently it is the largest circle tangent to the point on the inside of the curve. Given three mutually tangent circles, Descartes Theorem gives a formula to find the two circles which are tangent to each of the given three. The evolute of a curve is another curve traced by the center of an osculating circle as it travels along the given curve.
This tag should be used for questions relating to finding the osculating circle or evolute for a given curve or set of curves.
