如果三棱锥的底面积是S,高是h,那么它的体积是V=(1/3)Sh。课本利用“等底面积等高的任意两个锥体的体积相等”来证明这个定理。运用这个定理及其证法,可以简捷地解决立体几何中一个较麻烦的问题——求异面直线间的距离。例1 已知正方体AC_1棱长为a,试求BD与B_1C之间的距离。这类问题通常的解法是作图找出表示它们之间距离的线段,而后通过计算求得。求 If the bottom area of ​​the triangular pyramid is S, h is high, then its volume is V = (1/3) Sh. The textbook uses the equal volume of any two cones of equal floor area to prove this theorem. Using this theorem and its proofs, one of the more troublesome problems in solid geometry can be solved simply - finding the distance between lines of different surfaces. Example 1 Known cube AC_1 edge length a, try BD and B_1C distance between. The usual solution to this type of problem is to plot the lines that show the distance between them and then calculate them. begging