Standard Forms of Equations for Ellipses Centered at (0,0)
Horizontal Ellipse
The ellipse with center at the origin and equation x2a2+y2b2=1 (where
a>b) has vertices
(±a,0), endpoints of the minor axis
(0,±b), and foci
(±c,0), where
c2=a2−b2.
Vertical Ellipse
The ellipse with center at the origin and equation x2b2+y2a2=1 (where
a>b) has vertices
(0,±a),endpoints of the minor axis
(±b,0),and foci
(0,±c),where
c2=a2−b2.