public override double Length {get;}

{
  // nodes, edges of the triangle
  var triNnodes = triangle.Nodes;
  var triEdges = triangle.Edges;

  // triangle geometry
  polygon = triangle.ToPolygon();
  // triangle length
  var triLength = triangle.Length;
  // triangle area 
  var triArea = triangle.Area;
  // is the triangle "inside"
  var isInsideTriangle = triangle.IsInsideDataArea;

  // triangle aspect and slope  (radians)
  var aspect = triangle.Aspect;
  var slope = triangle.Slope;

  // get centroid
  var centroid = triangle.GetCentroid();

  // get normal
  var normal = triangle.GetNormal();

  // get adjacent triangles
  var adjTriangles = triangle.GetAdjacentTriangles();

  // get area of triangle that falls between the z values
  double minZ = 1.0;
  double maxZ = 3.0;
  IReadOnlyList<Coordinate3D> coords = triangle.GetPointsBetweenZs(minZ, maxZ);
}