“补形法”是把较复杂几何体向外延伸或补加,构成简单几何体。课本中不仅贯穿将复杂问题归结为简单问题的基本思想,而且较系统地给出补形方法。如在求斜棱柱侧面积时,是把斜棱柱的直截面下面部分,“补形”到上方组成直棱柱,在求圆台侧面积时,是把圆台侧面展开图,“补形”成圆锥侧面展开图。在求三棱锥体积时,是把它“补形”成一个三棱柱,然后再把这个三棱柱“割成”三个等积的三棱锥。在 “Complementary method” is to extend or add more complex geometry to form a simple geometry. Textbooks not only go through the basic idea of ​​resolving complex problems into simple ones, but also give a more systematic method of complementing. If the side area of ​​the inclined prism is calculated, the lower part of the straight section of the inclined prism is “complemented” to the upper part to form a straight prism. When the area of ​​the round table is determined, the side of the round table is expanded, and the “complement” is formed into a cone side. Expanded view. When calculating the triangular pyramid volume, it is “complemented” into a triangular prism, and then “triangulates” the triangular prism into three equal-area triangular pyramids. in