The mittenpunkt or middlespoint of a triangle ABC is the point of concurrence of the lines from the excenters D, E, F through the corresponding triangle side midpoints G, H, N. The mittenpunkt of triangle ABC is the symmedian point of the excentral triangle DEF. The point was studied by Christian Heinrich von Nagel in 1836.

I have used Geometry Expressions to visualize these geometric forms and check out a variety of conjectures. Geometry Expressions is the world's first Interactive Symbolic Geometry System. This means: Geometric figures can be defined by either Symbolic Constraints or numeric locations.

You can download Geometry Expressions 2 Free Trial. It is a fully featured 30 day evaluation copy of the software. All constraints, constructions and measurements are available for you to use.