在学习了“圆的认识”后,如果给你一张圆形纸片,没有标明圆心,你能找出圆的圆心吗?下面介绍三种找圆心的方法。一、折叠法。这种方法适用于易折叠的圆形物体。如图1所示,先把圆对折,使两个半圆完全重叠,这时圆中会出现一条折痕AB;然后再换一个角度,用同样的方法对折得到另一条折痕CD。这两条折痕(实际上就是 After learning “circle of understanding ”, if you give you a round of paper, did not indicate the center, you can find the center of the circle it? Here are three ways to find the center of the circle. First, the folding method. This method is suitable for folding circular objects. As shown in Figure 1, the first round of the fold, the two semicircles completely overlap, then the circle will appear a crease AB; and then another angle, in the same way fold to get another crease CD. These two creases (actually