在三棱柱\(ABC-A _{1} B _{1} C _{1}\)中,\(D\)是棱\(BC\)上的点\((\)不包括端点\()\),记直线\(B _{1} D\)与直线\(AC\)所成的角为\(θ _{1}\),直线\(B _{1} D\)与平面\(A _{1} B _{1} C _{1}\)所成的角为\(θ _{2}\),二面角\(C _{1} -A _{1} B _{1} -D\)的平面角为\(θ _{3}\),则\((\:\:\:\:)\)
在长方体\(ABCD-A _{1} B _{1} C _{1} D _{1}\)中,\(AB=AD=4\),\(AA _{1} =2\),过点,\(A _{1}\)作平面\(α\)与\(AB\),\(AD\)分别交于\(M\),\(N\)两点.若\(AA _{1}\)与平面\(α\)所成角为\(45°\),则截面\(A _{1} MN\)面积的最小值是\((\:\:\:\:)\)
在正三棱柱\((\)底面是正三角形的直三棱柱\()ABC-A _{1} B _{1} C _{1}\)中,\(AB=2\),\(E\),\(F\)分别为\(A _{1} C _{1}\)和\(A _{1} B _{1}\)的中点,当\(AE\)和\(BF\)所成角的余弦值为\( \dfrac {1}{4}\)时,\(AE\)与平面\(BCC _{1} B _{1}\)所成角的正弦值为\((\:\:\:\:)\)