3.如圖,在平面直角坐標(biāo)系中,拋物線y=x
2+(1-m)x-m交x軸于A,B兩點(diǎn)A在點(diǎn)B的左邊),交y軸負(fù)半軸于點(diǎn)C.
(1)如圖1,m=3,
①直接寫(xiě)出A,B,C三點(diǎn)的坐標(biāo);
②拋物線上存在點(diǎn)D,使得S
△ACD=2S
△ACO,直接寫(xiě)出D點(diǎn)的坐標(biāo);
(2)如圖2,設(shè)經(jīng)過(guò)A,B,C三點(diǎn)的⊙M交y軸于另外一點(diǎn)E,m=3?OE,經(jīng)過(guò)點(diǎn)M的直線y=kx+b(k≠0)交拋物線于G,H兩點(diǎn),若GH的長(zhǎng)等于⊙M的直徑長(zhǎng),求k
2的值.