设长宽高分别为x,y,z,则xyz=2S=2(xy+yz+zx) 是材料面积我们取f(x,y,z,s) = 2xy+2yz+2zx +k (xyz-2)这f对x,y,z,k的偏导数都是0时,函数取极小值所以xyz=22y+2z +kyz =02x +2z + kxz =02y +2x+ kxy =0上述方程关于x,y,z...