让我们从人教版数学教材九年级上册第23章第1节的一道有关正方形的例题说起:课本例题如图1,E是正方形ABCD中CD边上任意一点,以点A为中心,把△ADE顺时针旋转90°,画出旋转后的图形.这里的作图方法多样,除了教材上的方法以外,是不是还可以这样操作?以A为圆心,AE为半径作弧交CB的延长线于E′,则△ABE′为旋转后的图形. Let’s start with the example of a square in Chapter 9, Section 1, of Chapter XIX of the PEP Edition. The textbook example is shown in Figure 1, where E is any point on the edge of the CD in the square ABCD, centered on the point A, △ ADE clockwise rotation of 90 °, draw the rotated graphics. Here’s a variety of drawing methods, in addition to teaching methods, it is not also possible to do so? A center of the circle, Line at E ’, then △ ABE’ is the rotated graph.