Let's consider the following cases:

### A) ellipse with center in origin and horizontal major axis

Being **ç** focal half distance, the ellipse foci are **F _{1}**(-c, 0) and

**F**(c, 0):

_{2}Applying the definition of ellipse , we get the ellipse equation:

### B) ellipse with center in origin and vertical major axis

Under these conditions, the ellipse equation is: