4.
如图\(1\),在平面直角坐标系中,\(A(a,0)\),\(C(b,2)\),且满足\((a+2)^{2}+ \sqrt {b-2}=0\),过\(C\)作\(CB⊥x\)轴于\(B\).
\((1)\)求\(\triangle ABC\)的面积.
\((2)\)若过\(B\)作\(BD/\!/AC\)交\(y\)轴于\(D\),且\(AE\),\(DE\)分别平分\(∠CAB\),\(∠ODB\),如图\(2\),求\(∠AED\)的度数.
\((3)\)在\(y\)轴上是否存在点\(P\),使得\(\triangle ABC\)和\(\triangle ACP\)的面积相等?若存在,求出\(P\)点坐标;若不存在,请说明理由.