■サマーヴィルの等面四面体(その581)
【1】△5 in △4
P0(m/2,m√5/2,0,m√10/2,h)
P1(0,0,0,0,0)
P2(0,0,0,0,5h)
P3(2m,0,0,0,4h)
P4(3m/2,m√5/2,m√10/2,0,3h)
P5(m,m√5,0,0,2h)
としてみる.
P0P1^2=4m^2+h^2
P0P2^2=4m^2+16h^2
P0P3^2=6m^2+9h^2
P0P4^2=6m^2+4h^2
P0P5^2=4m^2+h^2
P1P2^2=25h^2
P1P3^2=4m^2+16h^2
P1P4^2=6m^2+9h^2
P1P5^2=6m^2+4h^2
P2P3^2=4m^2+h^2
P2P4^2=6m^2+4h^2
P2P5^2=6m^2+9h^2
P3P4^2=4m^2+h^2
P3P5^2=6m^2+4h^2
P4P5^2=4m^2+h^2
4m^2+h^2(5)<4m^2+16h^2(2)
6m^2+4h^2(4)<6m^2+9h^2(3)
25h^2(1)
25h^2=4m^2+h^2=5,h^2=1/5,m^2=6h^2=6/5
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a^2=4m^2+h^2(5)
b^2=6m^2+4h^2(4)
c^2=6m^2+9h^2(3)
d^2=4m^2+16h^2(2)
e^2=25h^2(1)
h^2を消去すると
a^2−4m^2=(b^2−6m^2)/4=(c^2−6m^2)/9=(d^2−4m^2)/16=e^2/25
b^2,c^2,d^2,e^2をa^2,m^2で表すと
b^2=4a^2−10m^2
c^2=9a^2−30m^2
d^2=16a^2−60m^2
e^2=25a^2−100m^2
10b^2=40a^2−100m^2
−10c^2=−90a^2+300m^2
5d^2=80a^2−300m^2
−e^2=−25a^2+100m^2
10b^2−10c^2+5d^2−e^2=5a^2 (OK)
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[まとめ] (m^2,h^2)システムからも同じ結果を導き出すことはできたが,やはり実験式という側面は否めない.
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