From the figure :
\The ellipse is centered at
.
Since it is centered at
the standard form of the equation of the ellicpse is
.
If
then
and
are lengths of major and minor axis.
If
then
and
are lengths of major and minor axis.
From the figure
and
.
Major axis of the ellipse is
.
Minor axis of the ellicpse is
.
Equation of the ellicpse can be obtained by substiuting
and
in the equation of the ellicpse
.

The equation of the ellicpse is
.
The ellipse which is in the form of
.
if
, then the foci is
where
.
if
, then the foci is
where
.

Therefore foci is at
.
The equation of the ellicpse is
and has foci at
.