N-PLURAL the locus of a point x, whose distance from two fixed points, a and b, is such that |x–a| |x–b| is a constant 卡西尼卵形线 [maths]
N-PLURAL（复数型名词） the locus of a point x, whose distance from two fixed points, a and b, is such that |x–a| |x–b| is a constant 卡西尼卵形线 [maths]