(a)[5]
State the equation of the normal to the curve at the point $(4,\ 4)$ in the form $y = mx + c$.
(b)[3]
Give the coordinates of the stationary point.
(c)[2]
State the nature of the stationary point.
(d)[4]
Find the exact area of the region enclosed by the curve, the $x$-axis and the lines $x = 0$ and $x = 4$.