相似三角形应用广泛,尤其在计算方面有它的独到之处,它常起到几何与代数之间相互沟通的桥梁作用。现举例如下:一、利用相似形求线段的长例1(如图1)在△ABC中,∠C=90°,D为BC上一点,若DE⊥AE,∠ADC=45°,DE∶AE=1∶5,BE=3,求△ABD的面积。解:在Rt△DEA中,设DE=x,则AE=5xAD=(5x)2 Similar triangles are widely used, especially in computing, which has its unique features. It often serves as a bridge between geometry and algebra. Here is an example: First, the use of similar shape line segment long example 1 (Figure 1) In △ ABC, ∠C = 90 °, D is a point on the BC, if DE ⊥ AE, ∠ ADC = 45 °, DE: AE=1:5, BE=3, find the area of ​​△ABD. Solution: In RtΔDEA, set DE=x, then AE=5xAD=(5x)2