■サマーヴィルの等面四面体(その379)
△3
P0(1,0,√2)
P1(0,0,0)
P2(1,√2,0)
P3(2,0,0)
P0P1=P1P2=P2P3=√3
P0P2=P1P3=2
P0P3=√3
試しに
P0(m,0,m√2,h)
P1(0,0,0,0)
P2(0,0,0,4h)
P3(m,m√2,0,3h)
P4(2m,0,0,2h)
とおくと,
P0P1^2=3m^2+h^2*
P0P2^2=3m^2+9h^2
P0P3^2=4m^2+4h^2
P0P4^2=3m^2+h^2*
P1P2^2=16h^2
P1P3^2=3m^2+9h^2
P1P4^2=4m^2+4h^2
P2P3^2=3m^2+h^2*
P2P4^2=4m^2+4h^2
P3P4^2=3m^2+h^2*
3m^2+h^2(4)<3m^2+9h^2(2)
4m^2+4h^2(3),16h^2(1)
H7は
P3P4=P4P5=P5P6=P6P7=√7
P3P5=P4P6=P5P7=√12
P3P6=P4P7=√15
P3P7=4
16h^2=16
3m^2+h^2=7
4m^2+4h^2=12
3m^2+9h^2=15
h^2=1,m^2=2は条件を満たす.
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