论文部分内容阅读
最近看到一份初二期末数学试卷,发现其中有一道探究性的好题. 题目把三边长为3cm、4cm、5cm的三角形与一个边长待定的直角三角形拼在一起,如果这两个三角形拼成一个等腰三角形,求这个等腰三角形的周长. 分析这两个三角形都是直角三角形,我们利用分类思想分为这两个三角形全等或不全等两类情况来思考.当两个三角形全等时,直角边所在的直线应是等腰三角形的对称轴.这又有两种可能,如图1
Recently, I saw a mathematics test paper at the end of the second and second grades and found that there was an inquiry question. The topic put together three triangles with 3cm, 4cm and 5cm lengths and a right-angled triangle to be determined if these two The triangles are combined into an isosceles triangle to find the perimeter of this isosceles triangle. Analysis of these two triangles is a right-angled triangle. We use the classification idea to divide the two triangles into equal or incomplete cases. When a triangle is congruent, the straight line where the right-angled edge lies should be the symmetry axis of the isosceles triangle. There are two possibilities, as shown in Figure 1.