1是圆
圆心(1/2,5),AB距离=√29,
故轨迹是=((x+1/2)^2+(y-5)^2=29
2、lg/2y/=lg16x+lg(x-2)化简4y^2=16x*(x-2)
3x=正负2,y=正负1,故s=4*2=8