四面体是最简单的多面体,有关四面体的性质和计算也是我们经常要遇到的。本文主要是举例说明如何用四面体的外接平行六面体来研究四面体的性质和解决它的有关计算。因为四面体的每两条对棱都不共面,因此可以作两个平行平面使其各通过其中一棱。通过三双对棱所作的三组平行平面围成一个平行六面体,叫做四面体的外接平行六面体。四面体的六条棱就分别是六面体六个面上 The tetrahedron is the simplest polyhedron, and the nature and calculation of the tetrahedron is something we often encounter. This article mainly illustrates how to use a tetrahedral circumscribed parallelepiped to study the properties of the tetrahedron and solve its calculations. Because every two pairs of tetrahedrons are not coplanar, two parallel planes can be made to pass through one of them. The three parallel planes made by the triple pairs of edges form a parallelepiped, a tetrahedral circumscribed parallelepiped. The six sides of the tetrahedron are the six sides of the hexahedron.