本刊文 [1 ]推出了椭圆和双曲线的四个姊妹圆 ,读后受益非浅 .在它的启示下 ,笔者进一步研究 ,又得到了一个优美有趣的姊妹圆 .命题 1　到椭圆 b2 x2 +a2 y2 =a2 b2 (a b0 )的两条准线和 x轴的交点的距离之比为a - cb (c为半焦距 )的点的轨迹为圆 (x± ae2 ) 2+y2 =(be2 ) 2 This article [1] introduced four sister circles of elliptic and hyperbolic curves. After reading it, they benefited greatly. In its inspiration, the author further studied and obtained a beautiful and interesting sister circle. Proposition 1 to oval b2 x2 The trajectory of the point where the ratio of the two guidelines of +a2 y2 =a2 b2 (a b0 ) to the intersection of the x-axis is a - cb (c is the semi-focal length) is the circle (x± ae2 ) 2+y2 =( Be2 ) 2