Thales & Constructibility

Part of the construction of the 17-gon, proved to exist by Gauss in 1796 but not found until nearly 30 years later.

This month's reading is the second half of Chapter 2 of Stillwell, starting from section 2.6. The reading is relatively short so this is a good opportunity to review and consolidate what we've done so far, or to catch up if you've fallen behind or joined us late (in which case, welcome!).

Section 2.6 finally delivers the proof of Thales' Theorem that we've waited so long for using the techniques developed earlier in the chapter. The exercises in section 2.8 point towards a profound connection between ruler-and-compass construction and arithmetic that we've been catching glimpses of all along, building on a technique developed in 2.7.

The optional discussion section (2.9) indicates some of the implications of all this, but Stillwell is ready to move on; this month sees us finishing the first of Stillwell's four "pillars", the one relating to axiomatic geometry, and preparing to move out of the ancient world and into the Renaissance.

 


 

The book can be purchased here (Amazon link). If you'd like to preview it first, we found an electronic copy hosted here (you need to register). The Moodle site, which has additional resources etc, is here: "enrol" on the course Shape Up using the key COXETER.

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  • Ravinder G.

    Apologies, something else requires my attention tonight. Will try to make it to the next one, and hopefully catch-up!

    March 12, 2013

  • Maxwell

    sorry guys won't be making it this time due to an emergency, this evening. Hope to see you guys next month.

    March 12, 2013

  • A former member
    A former member

    Hi everyone. I'm sorry I'll have spend the evening finishing my Phd funding application hence the last minute cancellation. Hope to see you next month.

    March 12, 2013

  • Ravinder G.

    Tentative.

    March 11, 2013

  • Ravinder G.

    Still haven't finished the first chapter!

    March 9, 2013

    • andrew m.

      you're welcome to join us. not all the activity is related to the Stillwell

      March 10, 2013

  • Ravinder G.

    Still haven't finished the first chapter!

    March 9, 2013

  • Maxwell

    will be there

    February 25, 2013

  • Elena

    I am going this time

    February 13, 2013

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