This means that you can get an ellipse by flattening a circle. Because one diameter of a circle is compressed, it becomes the short diameter of an ellipse.
Ellipse refers to the locus curve of the moving point P whose sum of distances from the fixed point F 1 and F2 on the plane is equal to a constant. An ellipse is a conic curve, that is, the tangent of a cone to a plane. The circumference of an ellipse is equal to the length of a specific sine curve in a period.