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- 性别
- 女
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456#
发表于 2012-12-29 07:48
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| I only know that a regular n-gon is constructible if and only if the Euler phi-function phi(n) is a power of two. As for a regular 17-gon, phi(17) = 16 because 17 is a prime number. 16 is two to the fourth power. Thus a 17-gon is constructible. |
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