For teaching geometry, it could be useful to have a website where one can enter the names of vertices of a polygon, specify which diagonals should be depicted, and specify the measures of certain angles, and have the website generate a credible figure.

What are some likely websites for this purpose, and what are their strengths or weaknesses for use in the classroom or mathematics lab?

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    $\begingroup$ geogebra.org $\endgroup$
    – Aeryk
    Aug 23, 2018 at 19:05
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    $\begingroup$ Make yourself familiar with geogebra's command line. It's quite powerful. $\endgroup$
    – Jasper
    Aug 23, 2018 at 21:01
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    $\begingroup$ Geogebra and Geometer's Sketchpad are some of the ones used most frequently in schools. That said, you may wish to check the more recent extension of Desmos to this area: desmos.com/geometry $\endgroup$ Aug 23, 2018 at 23:20
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    $\begingroup$ You can definitely use Geogebra without manually dragging. In addition to the command line, the various construction tools can usually be used to create a polygon to your exact specifications without ever dragging anything. $\endgroup$
    – mweiss
    Aug 24, 2018 at 1:41
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    $\begingroup$ I edited this because I think that the comments alone show there are plenty of teaching-oriented answers to what the essential question is here, even if it was formulated somewhat poorly. I hope this would be enough for reconsider the close votes. $\endgroup$
    – kcrisman
    Oct 10, 2019 at 1:49

1 Answer 1


Not an answer; just a tangential remark. In general it is not an easy problem to reconstruct a polygon from various sets of data. If the data does not uniquely determine the polygon, it would not be easy to "generate a credible figure," to quote the OP, compatible with the partial reconstruction.

For example, the paper below reconstructs a polygon from its "visibility angles," which do uniquely determine the polygon.

Chen, Danny Z., and Haitao Wang. "An improved algorithm for reconstructing a simple polygon from the visibility angles." In International Symposium on Algorithms and Computation, pp. 604-613. Springer, Berlin, Heidelberg, 2011. Elsevier link.

          Rec1 Rec2
          Fig. 1: Visibility angles at a vertex $v$. & Fig. 3.
Polygon reconstruction problems arise from the need for a mobile robot to navigate an environment using sensor/scanner measurements to avoid wall collisions. The Chen-Wang paper above cites 10 papers exploring a variety of reconstruction problems.


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