2022-11-17 ellipse △PF1F2=√4a(√a2−b2+a)((2√a2−b2+2a−a2(√a2−b2+t)2+b2(a2−t2)/a) (2√a2−b2+2a−a2(√a2−b2−t)2+b2(a2−t2)/a) T.theodor 2022.11.17.
