1,当为椭圆时,t^2>0t^2-1>0所以:t>祥碰1或t<-1当为双曲线时,t^2*(t^2-1)<0即:-12,当为椭圆时行毕:C^2=t^2-(t^2-1)=1C=+、-1当为双曲线时:C^2=t^2+(1-t^2)=1同样:C=+、-1满意请记得采纳啊,算是对我大清早跑来回答问题的安慰吧,谨带谈手好冷啊~~~~