“一母生两子,两子皆似母.”直角三角形斜边上的高将原直角三角形分为两个小直角三角形,这两个小直角三角形都和原直角三角形相似,这种基本图形我们不妨形象地叫做母子相似形.在母子相似形中有三个重要的结论(如图1):CD2=AD·BD,AC2=AB·AD,BC2=BA·BD, “A maternal two sons and two sons are like mothers.” The upper right triangle on the hypotenuse of the right-angled triangle is divided into two small right-angled triangles. These two small right-angled triangles are similar to the original right-angled triangles. The basic figure we may wish to image is called mother and child similar shape. There are three important conclusions in the mother-son similarity figure (Figure 1): CD2 = AD · BD, AC2 = AB · AD, BC2 = BA · BD,