Calculating resistance force parallel to a slope

[laurence_1]

1. An 80kg skier is skiing down a 5 degree slope at constant velocity. find

a) the resistance force parallel to the slope.

this should be a really easy question but i just don't know where to start. i have drawn out the vectors for parallel force and perpendicular force but do i not need more information to do the calculations?

 

[clamtrox]

Remember that he is moving at a *constant* velocity. When is velocity constant?