The functions are
and
.
Consider
.
Apply derivative on each side with respect to
.

.
Consider
.
Apply derivative on each side with respect to
.

.
Slope of the tangent line is first derivative of the curve.
\Slope of the curve is
.
Substitute
and
.
.
Slope of the tangent line is
.
Slope of the horizontal tangent line is 0.
\\
\


and
.
and
.
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
.
\
\




Substitute
in
and
.
.
.
Substitute
in
and
.
.
.
The points on the curve where the tangent line is vertical are
and
.
Check :
\Graph : The graph of the curve
and
.
.gif\")
Observe the graph of the curve notice that, the curve has horizontal tangent lines at the points
and
.and vertical tangent lines at
and
.
The points on the curve where the tangent line is horizontal are
and
.
The points on the curve where the tangent line is vertical are
and
.