Polygons Formed by Perpendicular Bisectors

A curious problem that was posted in the American Mathematical Monthly in 1953 waited for a solution for more than 40 years. Meanwhile it was written and talked about as an example of an unproven problem verified by the dynamic geometry software. Along the way several generalizations had been suggested.

Given a polygon Q = Q0, the perpendicular bisectors of its sides form another polygon Q1. In turn, the perpendicular bisectors of Q1 form a polygon Q2, and so on. It has been shown in 1997 that for quadrilaterals, Q2 is homothetic to Q. The question is, does their exist any relation between the n-gons Qi, i = 0, 1, ..., where n > 4?

The applet below might help in investigating that question. Good luck.

This applet requires Sun's Java VM 2 which your browser may perceive as a popup. Which it is not. If you want to see the applet work, visit Sun's website at https://www.java.com/en/download/index.jsp, download and install Java VM and enjoy the applet.

What if applet does not run?


  1. B. Grünbaum, Quadrangles, Pentagons, and Computers, Geombinatorics 3 (1993), pp. 4-9

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