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近几年来有关矩形问题在各种考试中频繁出现，问题情景不断创 新，其中折叠、旋转是矩形问题的主旋律，发现、探索是考查的目的．请 看下面的例题． 例1 如图所示，将矩形纸片 ABCD 沿虚线 EF 折叠，使点 A 落在点 C 上，点 D 落在点 H 上；然后再沿虚线 GH 折叠，使 B 落在点 E 上，点 C 落在点 F 上；折叠之后，剪一个直径在 BC 上的半圆，再展开，则展开后的图形为
In recent years, problems concerning rectangles have appeared frequently in various examinations, and problem scenarios have been continuously innovated. Among them, folding and rotation are the main theme of the rectangle problem. Discovery and exploration are the purpose of examination. Please see the following examples. Example 1 As shown in the figure, the rectangular paper sheet ABCD is folded along the dotted line EF so that the point A falls on the point C and the point D falls on the point H; then it is folded along the dotted line GH so that B falls on the point E. C falls on point F; after folding, cut a semicircle whose diameter is on BC, and expand, then the expanded figure is