在立体几何中,我们所遇到的极值的问题一般都是次数高于二次的函数或是分式函数的极值问题.对于没有学过导数的人,解这类问题都比较困难,特别对于中学学生,感到束手无策.但是,这些极值问题大多数是和面积,体积 In the three-dimensional geometry, the problem we encounter with extreme values ​​is generally a function of a number higher than a quadratic function or an extremum of a fractional function. For those who have not learned a derivative, it is difficult to solve such problems. Especially for secondary school students, they feel helpless. However, most of these extremum problems are