■DE群多面体の面数公式(その884)
321の基本単体の頂点は,ρについて
P0(0,0,0,0,0,0,0)
P1(1,0,0,0,0,0,0)
P2(1,1/√3,0,0,0,0,0)
P3(1,1/√3,1/√6,0,0,0,0)
P4(1,1/√3,1/√6,1/√10,0,0,0)
P5(1,1/√3,1/√6,1/√10,1/√15,0,0)
P6(1,1/√3,1/√6,1/√10,1/√15,1/√21,0)
P7(1,1/√3,1/√6,1/√10,1/√15,1/√21,√(9/7))
cosθ=21/{15+21}^1/2{21+7/9}^1/2
=21/6・3/14=3/4***
cosθ=√(7/9)/{21+7/9}^1/2=√(7/9)√(9/196)=√(1/28)
σについて
P0(0,0,0,0,0,0,0)
P1(1,0,0,0,0,0,0)
P2(1,1/√3,0,0,0,0,0)
P3(1,1/√3,1/√6,0,0,0,0)
P4(1,1/√3,1/√6,1/√10,0,0,0)
P5(1,1/√3,1/√6,1/√10,1/√15,0,0)
P6(1,1/√3,1/√6,1/√10,1/√15,√(2/6),0)
P7(1,1/√3,1/√6,1/√10,1/√15,√(2/6),1)
cosθ=15/{10+15}^1/2{15+3}^1/2=1/√2
cosθ=3/{15+3}^1/2{3+1}^1/2=1/2√2***
cosθ=1/{3+1}^1/2=1/2
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