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空间几何体的结构特征

> 19． (本小题满分12分) 如图，直四棱柱 ABCD— A 1 B 1 C 1 D 1的高为3，底面是边长为4且∠ DAB = 60°的菱形， AC BD = O， A 1 C 1 B 1 D 1 = O 1， E是 O 1 A的中点． (1) 求二面角 O 1－ BC－ D的大小； (2) 求点 E到平面 O 1 BC的距离．

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发布时间：2024-09-13

19． (本小题满分12分)
如图，直四棱柱 ABCD— A ₁ B ₁ C ₁ D ₁的高为3，底面是边长为4且∠ DAB = 60°的菱形， AC BD = O， A ₁ C ₁ B ₁ D ₁= O ₁， E是 O ₁ A的中点．
(1) 求二面角 O ₁－ BC－ D的大小；
(2) 求点 E到平面 O ₁ BC的距离．

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