(i)[4]
Find, showing all necessary working, the volume when the region enclosed by the curve, the $x$-axis and the lines $x = 1$ and $x = 2$ is rotated through $360^\circ$ about the $x$-axis.
(ii)[6]
Given that the line $2y = x + c$ is a normal to the curve, determine the possible values of the constant $c$.