\
(a)
\The function is
.
Differentiate on each side with respect to
.

Derivative of the secant function:
.
.
\
(b)
\Graph of the functions
and
in the interval
.
.gif\")
Observe the graph.
\The pattern of the slope of the derivative field is followed by the function
.
is derivative of
.
(a) 
(b)
\
is derivative of
.
.