■五芒星と掛谷の問題(その39)
(その32)をやり直し
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(rcosθ、rsinθ)と(rcos(π-2θ),rsin(π-2θ))=(-rcos2θ,rsin2θ)を結ぶ直線
y=(rsin2θ-rsinθ/(-rcos2θ-rcosθ)・(x-rcosθ)+rsinθ
(rcosθ、-rsinθ)と(1,0)を結ぶ直線
y=(rsinθ)/(1-rcosθ)(x-rcosθ)-rsinθ
の交点を求める
(rsin2θ-rsinθ)/(-rcos2θ-rcosθ)・(x-rcosθ)-(rsinθ)/(1-rcosθ)・(x-rcosθ)=-2rsinθ
{(rsin2θ-rsinθ)(1-rcosθ)-(rsinθ)(-rcos2θ-rcosθ)}・(x-rcosθ)=-2rsinθ(-rcos2θ-rcosθ)(1-rcosθ)
ここで、n=3の場合も計算できることになる。
{(2cosθ-1)(1-rcosθ)+r(cos2θ+cosθ)}・(x-rcosθ)=2r(cos2θ+cosθ)(1-rcosθ)
{2cosθ-1-2r(cosθ)^2+rcosθ+2r(cosθ)^2-r+rcosθ)}・(x-rcosθ)=2r(cos2θ+cosθ)(1-rcosθ)
{2cosθ-1+2rcosθ-r}・(x-rcosθ)=2r(cos2θ+cosθ)(1-rcosθ)
{2cosθ(1+r)-(1+r)}・(x-rcosθ)=2r(cos2θ+cosθ)(1-rcosθ)
(2cosθ-1)(1+r)・(x-rcosθ)=2r(cosθ+1)(2cosθ-1)(1-rcosθ)
(1+r)・(x-rcosθ)=2r(cosθ+1)(1-rcosθ)
x-rcosθ=2r(cosθ+1)(1-rcosθ)/(1+r)
y+rsinθ=(rsinθ)/(1-rcosθ)・(x-rcosθ)=2r(cosθ+1)(rsinθ)/(1+r)
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(rcosθ、rsinθ)と(rcos(π-2θ),rsin(π-2θ))=(-rcos2θ,rsin2θ)の中点((rcosθ-rcos2θ)/2,((rsinθ+rsin2θ)/2)
からの距離の2乗は
L^2={2r(cosθ+1)(1-rcosθ)/(1+r)+rcosθ-(rcosθ-rcos2θ)/2}^2+{2r(cosθ+1)(rsinθ)/(1+r)-rsinθ-((rsinθ+rsin2θ)/2}^2
{2r(cosθ+1)(1-rcosθ)/(1+r)+r(cosθ+cos2θ)/2}^2+{2r(cosθ+1)(rsinθ)/(1+r)-r(3sinθ+sin2θ)/2}^2
{2r(cosθ+1)(1-rcosθ)/(1+r)+r(cosθ+1)(2cosθ-1))/2}^2+{2r(cosθ+1)(rsinθ)/(1+r)-rsinθ(3+2cosθ)/2}^2
={r(cosθ+1)}^2{4(1-rcosθ)/2(1+r)+(1+r)(2cosθ-1))/2(1+r)}^2+(rsinθ)^2{2r(cosθ+1)/(1+r)-(3+2cosθ)/2}^2
={r(cosθ+1)}^2{(2cosθ(1-r)+3-r)/2(1+r)}^2+(rsinθ)^2{(2cosθ(1-r)+3-r)/2(1+r)}^2
=r^2(2cosθ+2){(2cosθ(1-r)+3-r)/2(1+r)}^2
=r^2(2cos(θ/2))^2{(2cosθ(1-r)+3-r)/2(1+r)}^2
=(rcos(θ/2))^2{(2cosθ(1-r)+3-r)/(1+r)}^2
=(rcos(θ/2))^2{(2cosθ(1-r)+3-r)/(1+r)}^2
(rcos(θ/2))^2{(2cos(θ/2))^2(1-r)+(1+r))/(1+r)}^2
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2Lと1+rの比較が問題となる
これにより結論自体を大きく変更せざるを得なくなった。
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r=1/6
n=3: 0.318123→0.526056
n=5: 0.359868→0.379365
n=7: 0.3719
n=9: 0.37692
n=11: 0.379476
n=13: 0.380951
n=21: 0.383251
n=41: 0.384308
n=61: 0.384515
n=81: 0.384588
n=101: 0.384623
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r=1/10
n=3: 0.214719→0.725685
n=5: 0.242886→0.51794
n=7: 0.251007→0.472759
n=9: 0.254395→0.455425
n=11: 0.25612→0.446916
n=13: 0.257116→0.4421
n=21: 0.258668→0.434724
n=41: 0.259382→0.431388
n=61: 0.259521→0.430741
n=81: 0.25957→0.430511
n=101: 0.259594→0.430403
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r=1/108
n=3: 0.0236169→6.00993
n=5: 0.0267152→4.2345
n=7: 0.0276084→3.85272
n=9: 0.0279811→3.70671
n=11: 0.0281709→3.63513
n=13: 0.0282804→3.59464
n=21: 0.0284511→3.53269
n=41: 0.0285296→3.50466
n=61: 0.0285449→3.49923
n=81: 0.0285504→3.4973
n=101: 0.0285529→3.49639
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