如图,正方体ABCD-A1B1C1D1中,E,F,G分别为AA1,A1D1,BC的中点,则异面直线EF与D1G所成角的大小为__________。

作者: tihaiku 人气: - 评论: 0
问题 如图,正方体ABCD-A1B1C1D1中,E,F,G分别为AA1,A1D1,BC的中点,则异面直线EF与D1G所成角的大小为__________。
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解析 连接AD1,AG,由于EF平行于AD1,则异面直线EF与D1G所成角等于AD1与D1G所成角。设正方体棱长为2,在△AD1G中,D1G=3,根据余弦定理,cos∠AD1G=
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