在求解二次函数最值问题中,求出二次函数的解析式是关键,往往要运用到代数、几何中的许多有关知识和技能,难度较大,这里结合教学实践,列举一些最值问题中解析式的求法。一、分割线段,求出二次函数解析式例1某建筑物的窗户如图1所示,它的上半部是半圆,下半部是矩形,制造窗框的材料总长(图中所有黑线的长度和)为15m。当x等于多少时,窗户的透 In solving the problem of the quadratic function, it is the key to find the analytic function of the quadratic function. It is often difficult to apply many related knowledge and skills in algebra and geometry. Here, some value issues are listed in combination with teaching practice. The middle analytical method. 1. Divide the line segment and find the quadratic function. Example 1 The window of a building is shown in Fig. 1. Its upper part is a semicircle and the lower part is a rectangle. The total length of the materials used to make the window frame (all black in the picture) The length and length of the line is 15m. When x is equal to how much, the window is transparent