共50条信息
平面\(a\)过正方体\(ABCD-A_{1}B_{1}C_{1}D_{1}\)的顶点\(A\),\(a/\!/\)平面\(CB_{1}D_{1}\),\(a\bigcap \)平面\(ABCD=m\),\(a\bigcap \)平面\({{ABB}}_{1}{A}_{1}=n\),则\(m\)、\(n\)所成角的正弦值为( )
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