在高三毕业班的综合复习中,我们曾用一个典型例子进行了一堂“求函数极值”的复习课,收到了较好的效果。例直角三角形ABC的直角边AB为定长a,它的内接正方形的一边在斜边BC上,试求△ABC的面积与内接正方形的面积之比的最小值。 1、画图、分析求函数关系式 In the comprehensive review of the third year graduating class, we used a typical example to conduct a review class of “exceeding function extremum” and received good results. For example, the right-angled edge AB of the right-angled triangle ABC is a fixed length a, and one side of its inscribed square is on the oblique side BC. Try to find the minimum value of the ratio of the area of ​​ΔABC to the area of ​​the inscribed square. 1, drawing, analysis of function relations