Further Questions about Tetrads
by Walter Trump

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Letter from Martin Gardner

  Enter the Tetrads Website  

Tetrads consist of four congruent regions which share boundaries with each of the three others.


An old tetrad from 1971 made of mirror symmetric tiles

This site discusses a recreational geometric puzzle. It is not a scientific publication.
After the introductory questions 1 to 3, the questions 4 to 8 are more autobiographical, and relate my own tetrad story. In the other chapters several old and new tetrads are discussed, mainly tetrads made of congruent polygons with certain properties. Also the construction principles of complicated tetrads are explained.

  Enter the Tetrads Website  

A symmetric tetrad with no hole made in February 2020. Two tiles surround the others completely.

  Enter the Tetrads Website  


A heptagon tetrad with a quadrilateral hole.       The correlations between the angles are noteworthy.

This tetrad was made in February 2020 and consists of four congruent pentagons.

  Enter the Tetrads Website  

 Walter Trump, Nürnberg, Germany, ms(at)trump.de, © 2020-02-12 (last modified: 2020-02-21)