AEP= 又∵∠ A= ∠ C=60 ° ∴△ APE ∽△ CQE 利用即 x xx2 12 1 xx0 90 0 90 CQ AP PC AE ?x xx x???66 2 1 Evaluation only. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 问题(2) 在运动过程中线段 ED 的长是否发生变化? 如果不变,求出线段的长; 如果发生改变,请说明理由. 解法一:用等边三角形性质进行解答解: 线段 DE 的长不变.由( 1)的解法(二)知 BD=DF 而△ APF 是等边三角形, PE ⊥ AF, ∴ AE=EF ∴ BD+AE=FD+EF 又(FD+EF)+(BD+AE)=AB =6, 即 ED+ED=6 ∴ ED=3 为定值,即 ED 的长不变 Evaluation only. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd.
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