计算几何体的面积和体积问题,是立体几何中一类比较常见的综合问题,往往需要运用立体几何中的多种知识、概念和方法.计算截面的面积时,首先要根据题目条件弄清楚截面的特征,然后才计算面积,即完成定位、定形定量三个步骤,其中定位是关键,注意截面的边数不大于所截几何体的面数. Calculating the area and volume of geometry is a common problem in three-dimensional geometry. It often requires the use of a variety of knowledge, concepts, and methods in the three-dimensional geometry. When calculating the area of ​​a cross-section, it is necessary to first clarify the cross-section according to the conditions of the problem. Characteristics, and then calculate the area, that is, complete the positioning, setting quantitative three steps, in which positioning is the key, note that the number of sides of the section is not greater than the number of faces of the truncated geometry.