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Two Geometry Puzzles

October 11, 2020 pm31 11:59 pm

I haven’t asked a math question in a long, long time. Not sure if anyone who does them is still reading…

Can a Polygon Be Constructed?

Under what circumstances is it possible, given n ≥ 3 segments, to form a polygon?

Or, if you prefer, under what circumstances, given n ≥ 3 segments, is it not possible to form a polygon?

The segments may be connected in any order.

Can a Quadrilateral, but not a Trapezoid, be Formed?

Are there four segments from which it is possible to construct a quadrilateral, but from which it is not possible to construct a trapezoid?

The segments may be connected in any order.

5 Comments leave one →
  1. October 12, 2020 am31 6:39 am 6:39 am

    Trapezoid is new to me, I’ll have to think about it when I’m more awake!

    • October 12, 2020 am31 9:03 am 9:03 am

      I thought about clarifying which definition of trapezoid, but not necessary.

      • October 12, 2020 pm31 12:06 pm 12:06 pm

        Ha! It does change the answer, though, doesn’t it?

    • October 12, 2020 pm31 12:03 pm 12:03 pm

      Okay, so, I am fairly confident that I know the answer for (b). I am pretty confident that I could work out the associated (messy?) algebra, but I wonder if there’s a good conceptual proof. Something with hinges?


  1. Playful Math Education 142 – Denise Gaskins' Let's Play Math

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