【单选题】Cirque du Soleil (say it: Serk du So-lay) is being accused of out-dated thinking about the dangers of AIDS. It is a modem acrobatic circus from Canada that tours in the United States and other countri...
【简答题】已知圆 O 1 : x 2 +6x+ y 2 -1=0 ,圆 O 2 : x 2 -6x+ y 2 -5=0 ,点P满足 k P O 1 ? k P O 2 =2 (1)求动点P的轨迹方程; (2)过点Q(1,2)能否做直线AB与P的轨迹交于A、B两点,并且使Q是AB的中点?如果存在,求出直线AB的方程;若不存在,请说明理由.