The curve is
and
.
Find the points on the curve where the tangent line is horizontal or vertical.
\Slope of the horizontal tangent line is 0.
\Slope of the vertical tangent line is
.
Find the slope of the curve.
\Consider
.
Differentiate on each side with respect to
.

Consider
.
Differentiate on each side with respect to
.

Slope of the tangent line is first derivative of the curve.
\Slope of the curve is
\
Substitute
and
in the above equation.

Slope of the tangent line is
.
Slope of the horizontal tangent line is 0.
\


or
.
Substitute
in
and
.

.
Substitute
in
and
.


The points on the curve where the tangent line is horizontal are
and
.
Slope of the vertical tangent line is
.



or
.
substitute
in
and
.

.
Now substitute
in
and
.

.
The points on the curve where the tangent line is vertical are
and
.
Check :
\The graph of the curve
and
.

Observe the graph:
\The curve has horizontal tangent lines at the points
and vertical line tangents at
.
The points on the curve where the tangent line is horizontal are
.
The points on the curve where the tangent line is vertical are
.