高中课本《平面解析几何》第１３１页例４是“化圆锥曲线的极坐标方程ρ＝ｅｐ１－ｅｃｏｓθ为直角坐标方程”，解题时涉及到方程ｘ２＋ｙ２＝ｅ（ｘ＋ｐ）（１）与两边平方后所得方程（１－ｅ２）ｘ２＋ｙ２－２ｅ２ｐｘ－ｅ２ｐ２＝０（２）的等价性问题．课本中有这样... High School Textbook “Plane Analytic Geometry” p. 131 Example 4 is “The polar equation of the conic section ρ=ep1-ecosθ is a Cartesian coordinate equation”. When solving the problem, it involves the equation x2+y2=e(x+p)(1) and the square of both sides. The equivalence of the resulting equation (1-e2)x2+y2-2e2px-e2p2=0(2). This is in the textbook...