二次函数中求三角形或四边形面积的最大值是一种常见题型.常见的思路是利用顶点坐标,通过分割组合转化为易求的三角形或梯形的面积,设出动点横坐标,建立面积与动点横坐标间二次函数模型,再转化为求二次函数最大值.关键是分割组合,建立二次函数.下面从另一个视角探究此类题的解法,供读者学习和赏析. Finding the maximum value of a triangle or quadrilateral in a quadratic function is a common question type. The common idea is to use vertex coordinates to convert an easily-triangulated triangle or trapezoidal area by segmentation and combination, set the out-point of the moving point, and establish the area. The quadratic function model of the moving point is transformed into the quadratic function maximum. The key is to divide the combination and establish the quadratic function. The following is the solution to this type of problem from another angle of view, for readers to learn and appreciate.