又一类三次李氏卵圆
A New Kind of Cubic Li’s Oval

本文提出了李氏卵圆的定义，及卵圆的卵心，卵圆的长半径、短半径和对称半径等相关概念的定义。给出一类三次方程，并证明其为李氏卵圆方程。推出了某些三次方程为李氏卵圆方程的判定定理，及此类李氏卵圆的周长、面积和旋转卵球体的表面积和体积。
A definition of Li’s oval is provided, and the definitions of the oval center, and the long radius, and the short radius, and the symmetrical radius of the oval are provided. A kind of cubic equation is given and proved to be Li’s oval equation. The judgment theorems that some cubic equations are Li’s oval equation is derived, the perimeter and area of Li’s oval and the surface area and volume of rotating oval ball are deduced.