特殊的三角函数方程组
假设\(t_1,t_2,\ldots,t_n \in (0,\frac{2\pi}{3}]\)且满足下列方程组,求解下列参数\(t_1,t_2,\ldots,t_n, n\in\rm I\!N^+\)\(\sin(t_1)-\sin(t_2+t_3)+\sin(t_4)=m\)..........................................(1)
\(\sin(t_2)-\sin(t_3+t_4)+\sin(t_5)=m\)..........................................(2)
\(\sin(t_3)-\sin(t_4+t_5)+\sin(t_6)=m\)..........................................(3)
\(.......................................................................\)
\(\sin(t_{n})-\sin(t_1+t_2)+\sin(t_3)=m\)......................(n)
\(t_1+t_2+\ldots+t_n=2\pi\).............................................................(n+1)
当\(n=3\)时,\(t_1=t_2=t_3=\frac{2\pi}{3},m=\frac{3\sqrt{3}}{2}\)
当\(n=4\)时,\(t_1=t_3=\alpha,t_2=t_4=\pi-\alpha\)
n条方程你写错了吧?应该是循环对称?
是用于求什么极值的?
本题来源于<一般折线几何学>P141~142 凸N边形中的费马问题:
设\(X\)为凸N边形\(A_1A_2...A_n\)内任一点,记\(\angle A_1XA_2=\alpha_1,\angle A_2XA_3=\alpha_2 \ldots \angle A_nXA_1=\alpha_n\)
定理4.23:设\(A_1A_2...A_n\)为凸\(n\)边形,如果存在一点X_0,满足条件\(\frac{p_i}{\sin(\alpha_{i-1})-\sin(\alpha_i+\alpha_{i+1})+\sin(\alpha_{i+2})}=M(常数)\),\(i=1,2\ldots,n\),\(\alpha_{n+1}=\alpha_1,\alpha_{n+2}=\alpha_2\),那么X_0就是凸N边形上的加权费马点:
\(p_1A_1X_0+p_2A_2X_0+\ldots+p_nA_nX_0=\min (p_1A_1X+p_2A_2X+\ldots+p_nA_nX)\),
我主要想说的是:
本主题除了平凡解\(t_1=t_2=\ldots=t_n=\frac{2\pi}{n}, m=2\sin(\frac{2\pi}{n})-\sin(\frac{4\pi}{n})\)外,其它非平凡解是否存在,如何求解?
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