■等面単体の体積(その397)

 超平面

  −x+√5y+√10z=0

からそれぞれの点までの距離は,符号もつけて

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

  P2(2,0,0,0):−2/4

  P3(3/2,(√5)/2,(√10)/2,0):6/4

  P4(1,√5,0,0):4/4

  P0(0,0,0,0)

  P1(m,m√2,0,−h)

  P2(m,m√2,0,3h)

  P3(2m,0,0,2h)

  P0P1^2=3m^2+h^2

  P0P2^2=3m^2+9h^2

  P0P3^2=4m^2+4h^2

  P1P2^2=16h^2

  P1P3^2=3m^2+9h^2

  P2P3^2=3m^2+h^2

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

  P0(0,0,0,2h)

  P1(m,m√2,0,−h)

  P2(m,m√2,0,3h)

  P3(2m,0,0,0)

  P0P1^2=3m^2+9h^2

  P0P2^2=3m^2+h^2

  P0P3^2=4m^2+4h^2

  P1P2^2=16h^2

  P1P3^2=3m^2+h^2

  P2P3^2=3m^2+9h^2

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

  P1P2=P2P3=P3P4=2

  P1P3=P2P4=√6

  P1P4=√6

より,

  3m^2+h^2=16h^2→m^2=5h^2

  3m^2+9h^2=4m^2+4h^2  (OK)

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[まとめ]hの与え方が等間隔ではなくなっている.

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