Hello, s3a!

I don't understand what you were taught . . .In the following I determined the value of to be 6 . How?

but I can't find the value of . Really?

and therefore cannot find the value of

Find the coordinates of the foci of an ellipse centred at the origin,

whose vertices have the coordinates: (8, 0) and (0, -4).

The center is at the origin:

. . So the vertices are at: .

This tell usthat: .immediately

And is given by: .