Tridentix

Suppose we are given two fixed points. Then we consider the sum of distances from an arbitrary chosen point to the first and to the second fixed point. A rotation ellipsoid is the set of all points, the distance sum of which is equal to a fixed value. This model extends this concept to three fixed points, especially to the edges of an equilateral triangle. The surface consists of all points, the distance sum of which is equal to twice the triangle side. Please refer to the nutshell models for another set of shapes. And yes, this has nothing to do with squares.