The equation is
where
and
.
Consider the equation
.

.
The equation is in the general form of parabola
where
is vertex, focus is
and directrix is
.
Compare the equation with general form.
\Here
.
.
The equation of the parabola with vertix at
and the axis of symmetry is about
-axis.
The focus is
and the directrix is
.
The parabola is opens right when
and opend left when
.
The equation of the parabola with vertix at
and the axis of symmetry is about
-axis.
The focus is
and directrix is
.