keskiviikko 23. maaliskuuta 2011

Albrecht Dürerin (1471–1528) harppi-viivain konstruktio säännöllisestä viisikulmiosta

This construction has two notable features. One is that it is drawn using a rusty compass—that is, the compass is set to one opening for the entire construction. This was probably a great bonus to the artisan; I imagine that not having to continually adjust the compass made the construction fast and accurate. The second interesting fact is that it is only approximately a regular pentagon—but it is a very good approximation. By my calculations, the error in the height of the pentagon is less than 1%. The construction is shown below. You begin with the line segment labeled and you set the compass to this radius (lähde).

Liikuta sinisiä pisteitä.

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