displacement $d.$

Determine the following.

$($a$)$ the work done $($in J$)$ by the net force component Fcos$()$ acting on the rollerblader as he moves from $0$ to $5\mathrm{.}0m$

$($b$)$ the work done $($in J$)$ by the net force component Fcos$()$ acting on the rollerblader from $5\mathrm{.}0m$ to $10\mathrm{.}0m$ J