1976 USAMO 第 4 题

If the sum of the lengths of the six edges of a trirectangular tetrahedron $PABC$ (i.e., $\angle APB=\angle BPC=\angle CPA=90^o$) is $S$, determine its maximum volume.

如果三角四面体$PABC$(即$\angle APB=\angle BPC=\angle CPA=90^o$)的六个边的长度之和为$S$，请确定其最大体积。