GbEng
角距离,是由一定点到两物体之间所量度的夹角。 Angular distance is the distance between two objects measured as an angle from a given point.
抛物线到一固定直线和不在直线上某一固定点等距的点的轨迹所形成的平面曲线 A plane curve formed by the locus of points equidistant from a fixed line and a fixed point not on the line.