如图,直角梯形ABCD与等腰直角三角形ABE所在的平面互相垂直.AB∥CD,AB⊥BC,AB=2CD=2BC,EA⊥EB.
(Ⅰ)求证:AB⊥DE;
(Ⅱ)求直线EC与平面ABE所成角的正弦值;
(Ⅲ)线段EA上是否存在点F,使EC∥平面FBD?若存在,求出
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103102354187250055/SYS201311031023541872500019_ST/0.png)
;若不存在,说明理由.
考点分析:
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