由题:x/a+y/b+z/c=1a/x+b/y+c/z=0(x/a+y/b+z/c)^2=1(x/a)^2+(y/b)^2+(z/c)^2+2xy/ab+2yz/bc+2zx/ca=1(x/a)^2+(y/b)^2+(z/c)^2+2xyz/abc(a/x+b/y+c/z)=1由于a/x+b/y+c/z=0(x/a)^2+(y/b)^2+(z/c)^2=1证毕。
该方程从何而来？
