如圖,已知直線

交坐標(biāo)軸于A,B兩點(diǎn),以線段AB為邊向上作正方形ABCD,過點(diǎn)A,D,C的拋物線與直線的另一個(gè)交點(diǎn)為E.
(1)直接寫出點(diǎn)C和點(diǎn)D的坐標(biāo),C(______);D(______);
(2)求出過A,D,C三點(diǎn)的拋物線的解析式及對(duì)稱軸;
(3)探索:過點(diǎn)E作平行于y軸的直線上是否存在點(diǎn)P,使△PBC為直角三角形?若存在,請(qǐng)求出P點(diǎn)坐標(biāo);若不存在,請(qǐng)說明理由.
