■サマーヴィルの等面四面体(その564)

【1】F6 in F5

△6を

P0(m√(1/2),0,m√(1/2),m,m√3,h)

P1(0,0,0,0,0,0)

P2(0,0,0,0,0,6h)

P3(m√2,m√3,0,0,0,5h)

P4(m√8,0,0,0,0,4h)

P5(m√(9/2),0,m√(9/2),0,0,3h)

P6(m√2,0,m√2,2m,0,2h)

としてみる.

  P0P1^2=5m^2+h^2

  P0P2^2=5m^2+25h^2

  P0P3^2=8m^2+16h^2

  P0P4^2=9m^2+9h^2

  P0P5^2=8m^2+4h^2

  P0P6^2=5m^2+h^2

  P1P2^2=36h^2

  P1P3^2=5m^2+25h^2

  P1P4^2=8m^2+16h^2

  P1P5^2=9m^2+9h^2

  P1P6^2=8m^2+4h^2

  P2P3^2=5m^2+h^2

  P2P4^2=8m^2+4h^2

  P2P5^2=9m^2+9h^2

  P2P6^2=8m^2+16h^2

  P3P4^2=5m^2+h^2

  P3P5^2=8m^2+4h^2

  P3P6^2=9m^2+9h^2

  P4P5^2=5m^2+h^2

  P4P6^2=8m^2+4h^2

  P5P6^2=5m^2+h^2

5m^2+h^2(6)<5m^2+25h^2(2)

8m^2+4h^2(5)<8m^2+16h^2(3)

9m^2+9h^2(4)

36h^2(1)

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P0を外すと,等間隔ではなくなる点に注意して

  P1P2^2=36h^2

  P1P3^2=5m^2+25h^2

  P1P4^2=8m^2+16h^2

  P1P5^2=9m^2+9h^2

  P1P6^2=8m^2+4h^2

  P2P3^2=5m^2+h^2

  P2P4^2=8m^2+4h^2

  P2P5^2=9m^2+9h^2

  P2P6^2=8m^2+16h^2

  P3P4^2=5m^2+h^2

  P3P5^2=8m^2+4h^2

  P3P6^2=9m^2+9h^2

  P4P5^2=5m^2+h^2

  P4P6^2=8m^2+4h^2

  P5P6^2=5m^2+h^2

36h^2(1)=5m^2+h^2(4)<5m^2+25h^2(1)

8m^2+4h^2(4)<8m^2+16h^2(2)

9m^2+9h^2(3)

36h^2(1)

F6は

  P1P2=P2P3=P3P4=P4P5=P5P6=√6

  P1P3=P2P4=P3P5=P4P6=√10

  P1P4=P2P5=P3P6=√12

  P1P5=P2P6=√12

  P1P6=√10

であるから,

 36h^2=5m^2+h^2=6,8m^2+4h^2=10

 9m^2+9h^2=12,8m^2+16h^2=12,

 5m^2+25h^2=10,m^2=7h^2

 h^2=1/6,m^2=7/6

===================================

 また,

P1(0,0,0,0,0,0)

P2(0,0,0,0,0,6h)

P3(m√2,m√3,0,0,0,5h)

P4(m√8,0,0,0,0,4h)

P5(m√(9/2),0,m√(9/2),0,0,3h)

P6(m√2,0,m√2,2m,0,2h)

のQ(x,y,z,w,v)がF5を形成すればよいのであるが,

  P2P3^2=5m^2

  P2P4^2=8m^2

  P2P5^2=9m^2

  P2P6^2=8m^2

  P3P4^2=5m^2

  P3P5^2=8m^2

  P3P6^2=9m^2

  P4P5^2=5m^2

  P4P6^2=8m^2

  P5P6^2=5m^2

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【2】G6 in G5

 次に外すとなったら,P6だろうか? この場合も等間隔ではなくなる点に注意して

  P1P2^2=36h^2

  P1P3^2=5m^2+25h^2

  P1P4^2=8m^2+16h^2

  P1P5^2=9m^2+9h^2

  P2P3^2=5m^2+h^2

  P2P4^2=8m^2+4h^2

  P2P5^2=9m^2+9h^2

  P3P4^2=5m^2+h^2

  P3P5^2=8m^2+4h^2

  P4P5^2=5m^2+h^2

36h^2(1)=5m^2+h^2(3)<5m^2+25h^2(1)=

8m^2+4h^2(2)<8m^2+16h^2(1)=

9m^2+9h^2(2)

G6は

  P2P3=P3P4=P4P5=P5P6=√6

  P2P4=P3P5=P4P6=√10

  P2P5=P3P6=√12

  P2P6=√12

であるから,

 36h^2=5m^2+h^2=6,5m^2+25h^2=8m^2+4h^2=10

 9m^2+9h^2=8m^2+16h^2=12,

 h^2=1/6,m^2=7/6はこれらを満たす.

===================================

 また,

P1(0,0,0,0,0,0)

P2(0,0,0,0,0,6h)

P3(m√2,m√3,0,0,0,5h)

P4(m√8,0,0,0,0,4h)

P5(m√(9/2),0,m√(9/2),0,0,3h)

のQ(x,y,z,w,v)がF5を形成すればよいのであるが,

  P2P3^2=5m^2

  P2P4^2=8m^2

  P2P5^2=9m^2

  P3P4^2=5m^2

  P3P5^2=8m^2

  P4P5^2=5m^2

===================================

【3】H6 in H5

 次に外すとなったら,P5だろうか? この場合も等間隔ではなくなる点に注意して

  P1P2^2=36h^2

  P1P3^2=5m^2+25h^2

  P1P4^2=8m^2+16h^2

  P2P3^2=5m^2+h^2

  P2P4^2=8m^2+4h^2

  P3P4^2=5m^2+h^2

36h^2(1)=5m^2+h^2(2)<5m^2+25h^2(1)=

8m^2+4h^2(1)<8m^2+16h^2(1)

H6は

  P3P4=P4P5=P5P6=√6

  P3P5=P4P6=√10

  P3P6=√12

であるから,

 36h^2=5m^2+h^2=6,5m^2+25h^2=8m^2+4h^2=10

 8m^2+16h^2=12

 h^2=1/6,m^2=7/6はこれを満たす.

===================================

P1(0,0,0,0,0,0)

P2(0,0,0,0,0,6h)

P3(m√2,m√3,0,0,0,5h)

P4(m√8,0,0,0,0,4h)

 Q(x,y,z,w,v)がH5を形成すればよいのであるが,

  P2P3^2=5m^2

  P2P4^2=8m^2

  P3P4^2=5m^2

これが(5,5,8)なので(OK).

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