27.如图,在长方体ABCD−A1B1C1D1ABCD-A_{1}B_{1}C_{1}D_{1}ABCD−A1B1C1D1中,AB=3AB=3AB=3,AD=AA1=2AD=AA_{1}=2AD=AA1=2,点EEE在ABABAB上,且AE=1AE=1AE=1.(Ⅰ)求直线BC1BC_{1}BC1与A1CA_{1}CA1C所成角的大小;(Ⅱ)求BC1BC_{1}BC1与平面A1ECA_{1}ECA1EC所成角的正弦.