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椭园、抛物线、双曲线统称为二次曲线或园锥截线，因为它们具有共性：在直角坐标系中的方程都是二次的或都可由平面截园锥而得来。但椭园、抛物线、双曲
Ellipse, parabola, and hyperbola are collectively referred to as quadratic curves or cones, because they have commonalities: the equations in the Cartesian coordinate system are all quadratic, or both can be derived from the plane interceptor. But elliptical, parabolic, double