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如图,边长为a的正△ABC的中线AF与中位线DE相交于G,已知△A′ED是△AE...
如图,边长为a的正△ABC的中线AF与中位线DE相交于G,已知△A′ED是△AED绕DE旋转过程中的一个图形,现给出下列命题,其中正确的命题有
.(填上所有正确命题的序号)
(1)动点A′在平面ABC上的射影在线段AF上;
(2)三棱锥A′-FED的体积有最大值;
(3)恒有平面A′GF⊥平面BCED;
(4)异面直线A′E与BD不可能互相垂直.
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考点分析:
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