如图,在多面体\(ABCA_{1}B_{1}C_{1}\)中,四边形\(ABB_{1}A_{1}\)是正方形,\(CA⊥\)平面\(ABB_{1}A_{1}\),\(AC=AB=1\),\(B_{1}C_{1}/\!/BC\),\(BC=2B_{1}C_{1}\).
\((\)Ⅰ\()\)求异面直线\(CA_{1}\)与\(BC_{1}\)所成角的正切值;
\((\)Ⅱ\()\)求证:\(AB_{1}/\!/\)平面\(A_{1}C_{1}C\);
\((\)Ⅲ\()\)若点\(M\)是\(AB\)上的一个动点,试确定点\(M\)的位置,使得二面角\(C-A_{1}C_{1}-M\)的余弦值为\( \dfrac {1}{3}\).