Hello, tomkoolen!

Ellipse with foci (0,4) and (6,4) and the length of the long axis is 14.

You are expected to know the general formula for an ellipse: .

. . where is the center,

. . and and are the lengths of the semiaxes.

Also , the distance from the center to a focus, is given by:

Since the ellipse is "horizontal",Code:| | * * * * | : * * | : * * | :b * | : * F1| C: F2 * * - - o - - o - - o - - * * (0,4) : (6,4) * | : * | : * * | : * ------*-+-----:-------*------ | * * * | : - a=7 - :

The center is halfway between the foci:.

We have: .

Hence: .

The equation is: .