作DC1中点M,连接ME,D1C
∵M,E分别为D1C,BC中点
∴ME为△D1BC的中位线
∴D1B‖ME
∵ME在平面C1DE内
而 BD1不在平面C1DE内
∴BD1‖平面C1DE
有些符号打不出,你自己写的时候注意下拉~
正方体ABCD-A1B1C1D1中,E为BC中点,求证BD1平行于平面CIDE
正方体ABCD-A1B1C1D1中,E为BC中点,求证BD1平行于平面CIDE
急
简单思路即可
急
简单思路即可
数学人气：871 ℃时间：2019-11-18 22:13:34
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