evolute

/ev-uh-loot or, especially British, ee-vuh-/US // ˈɛv əˌlut or, especially British, ˈi və- //UK // (ˈɛvəˌluːt) //

坚决不动摇,坚决执行,坚决,坚决反对

Definitions

n.名词 noun

1
Geometry.
- : the locus of the centers of curvature of, or the envelope of the normals to, another curve.Compare involute.

The adjective translated evolute (udanh) is of frequent occurrence in the formulas, but has no exact equivalent in English.
The evolute of a curve is the curve which is the envelope of all its normals or the locus of all its centres of curvature.
These names are given to the curves because the end of a stretched thread unwound from the evolute will describe the involute.
The locus of the centres of curvature, or envelope of the normals, of a curve is called the “evolute.”
The involutes are “orthogonal trajectories” of the tangents to the common evolute.