5.
\((1)\)在\(Rt\triangle ABC\)中,\(∠ABC=90^{\circ}\),\(AB=3\),\(BC=4\),将三角形绕直角边\(AB\)旋转一周所成的几何体的体积为 ______ .
\((2)\)如图所示,\(O\)是正方体\(ABCD-A_{1}B_{1}C_{1}D_{1}\)对角线\(A_{1}C\)与\(AC_{1}\)的交点,\(E\)为棱\(BB_{1}\)的中点,则空间四边形\(OEC_{1}D_{1}\)在正方体各面上的投影不可能是 ______