如图所示,四边形ABCD是正方形,点E是边BC的中点且∠AEF=90°,EF交正

如图所示,四边形ABCD是正方形,点E是边BC的中点且∠AEF=90°,EF交正方形外角平分线CF于点F,取边AB的中点G,连接EG.
(1)求证:EG=CF;
(2)将△ECF绕点E逆时针旋转90°,请在图中直接画出旋转后的图形,并指出旋转后CF与EG的位置关系.

答案

(1)证明:∵正方形ABCD,点G,E为边AB、BC中点,
∴AG=EC,△BEG为等腰直角三角形,
∴∠AGE=180°﹣45°=135°,
又∵CF为正方形外角平分线,
∴∠ECF=90°+45°=135°,
∴∠AGE=∠ECF,
∵∠AEF=90°,
∴∠GAE=90°﹣∠AEB=∠CEF,
∴△AGE≌△ECF,
∴EG=CF;
(2)画图如图所示,
旋转后CF与EG平行.解析:

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