题:圆台上下底面的面积分别为S1、S2,一个平行于底面的截面把圆台的高分成两部分,若上下两部分之比为λ,则该截面的面积为( ). 笔者在做该题时通过把圆台补成圆锥,利用平面、几何知识得出答案(B).事后一思考,觉得用解析法解该题更完美. Problem: The area of ​​the upper and lower bottom surfaces of the circular table is S1 and S2. A section parallel to the bottom surface divides the height of the circular table into two parts. If the ratio of the upper part to the lower part is λ, then the area of ​​the section is (). The author is doing this question. By making the cone into a cone and using plane and geometry knowledge to arrive at the answer (B), afterwards thinking that it would be more perfect to use an analytical method to solve the problem.