焦点
focus (plural: foci) One of the two fixed points in the definition of an ellipse; the sum of distances from any point on the ellipse to the foci is constant.
CSCA 数学 考试术语
focus (plural: foci) One of the two fixed points in the definition of an ellipse; the sum of distances from any point on the ellipse to the foci is constant.
CSCA 数学 考试术语