
如图,正方体\(ABCD-A _{1} B _{1} C _{1} D _{1}\)的棱长为\(1\),则下列四个命题正确的有\((\:\:\:\:)\)
①直线\(BC\)与平面\(ABC _{1} D _{1}\)所成的角等于\( \dfrac {π}{4}\);
②点\(C\)到平面\(ABC _{1} D _{1}\)的距离为\( \dfrac { \sqrt {2}}{2}\);
③两条异面直线\(D _{1} C\)和\(BC _{1}\)所成的角为\( \dfrac {π}{4}\);
④三棱柱\(AA _{1} D _{1} -BB _{1} C _{1}\)外接球半径为\( \dfrac { \sqrt {3}}{2}\).