■サマーヴィルの等面四面体(その832)

 B=b^2について整理してみたい.

144V^2=−a^2(c^2−a^2)^2+b^4(3a^2−2b^2+c^2)

  c^2=3(b^2−a^2)

144V^2=−a^2(c^2−a^2)^2+b^6

  4c^2=36a^2−36

  4c^2=9b^2−9

  4a^2=b^2+3,(c^2−a^2)=2b^2−3

144V^2=−(b^2+3)/4・(2b^2−3)^2+b^6

4・144V^2=−(b^2+3)・(2b^2−3)^2+4b^6

4・144V^2=−(B+3)・(2B−3)^2+4B^3

4・144V^2=−(B+3)・(4B^2−12B+9)+4B^3

=−4B^3+12B^2−9B−12B^2+36B−27+4B^3

=27B−27

B=1,C=0,A=1  (NG)

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 A=a^2について整理してみたい.

144V^2=−a^2(c^2−a^2)^2+b^6

  4c^2=36a^2−36

  4c^2=9b^2−9

  4a^2=b^2+3,(c^2−a^2)=2b^2−3=8a^2−9

144V^2=−a^2・(8a^2−9)^2+(4a^2−3)^3

=−A・(8A−9)^2+(4A−3)^3

=27A−27

A=1,C=0,N=1  (NG)

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