1.已知圓W經(jīng)過(guò)
三點(diǎn).
(1)求圓W的方程.
(2)若經(jīng)過(guò)點(diǎn)P(-1,0)的直線l
1與圓W相切,求直線l
1的方程.
(3)已知直線l
2與圓W交于M,N(異于A點(diǎn))兩點(diǎn),若直線AM,AN的斜率之積為2,試問(wèn)直線l
2是否經(jīng)過(guò)定點(diǎn)?若經(jīng)過(guò),求出該定點(diǎn)坐標(biāo);若不經(jīng)過(guò),請(qǐng)說(shuō)明理由.