5.
如图,已知四边形\(ABCD\),\(AB/\!/x\)轴\(/\!/CD\),\(AD/\!/BC\),\(AB=CD=6\),点\(A\)的坐标是\((1,-4)\),点\(C\)的坐标是\((3,4)\),点\(B\)在第四象限,\(AD\)与\(y\)轴交于点\(G\),
备用图
\((1)①\)求出点\(D\)的坐标
\(②\)直接写出直线\(AD\)的解析式为_____________________.
把直线\(BC\)看成是由直线\(AD\)向右平移\(6\)个单位长度后得到的,则直线\(BC\)的解析式为_____________ .
\((2)\)若点\(P\)在边\(AD\)上,当\(P\)点的纵坐标为\(2\)时,点\(P\)关于直线\(x=a\)的对称点为\(P^{/}\)恰好落在\(BC\)边上时,请直接写出\(a\)的值。\(a = \)_________ .
\((3)\)若点\(Q\)在边\(AB\)或\(CD\)上,过点\(Q\)作\(QM/\!/y\)轴,过点\(G\)作\(GM/\!/x\)轴,它们交于点\(M\),将\(\triangle QGM\)沿直线\(GQ\)翻折,当点\(M\)的对应点落在\(y\)轴上时,直接写出点\(Q\)的坐标。