大家都知道圓錐曲线可定义为动点的軌迹,該动点到一定点和一定直线的距离的此恆为常数。这个常数称为离心率,定点称为焦点,定直线称为准綫。若取焦点F为极点,F到准线g的垂綫作极軸,垂足D到F的方向为极軸的正向,如此选定极坐标系以后,則以e为离心率的圓錐曲綫的方程应为 Everyone knows that a conic curve can be defined as a trajectory of a moving point, and the constant of the distance from the fixed point to a certain straight line is a constant. This constant is called the eccentricity, the fixed point is called the focus point, and the straight line is called the quasi-line. If the focal point F is taken as the pole, the perpendicular line from F to the guideline g is used as the polar axis, and the direction from D to F is the positive direction of the polar axis. After selecting the polar coordinate system, the eccentric curve with e as the eccentricity is selected. The equation should be