How Can Cross Products Help Solve Vector Problems?

[huronjubal]

Homework Statement

[PLAIN]http://img715.imageshack.us/img715/8128/66497284.jpg

Homework Equations

The Attempt at a Solution

I'm really confused about this question and not sure what to do. I've only been able to find the angles and don't really know what to do next. I also think that it i might need to know how to do cross products to find the expression but I'm not sure, since i haven't really learned about it yet. so i would not know when and how to apply it to this problem. If anyone can give me on how i should proceed in doing the problem in a. thanks.

Edit:
So I've tried to draw a perpendicular line from end of F to AB and would get something like this
Fab = Fcos55
i've actually thought of this before but I'm not so sure if this would be allowed, like if it's breaking any rules or somthing

 

[pongo38]

Start by drawing a triangle in which the sides are parallel to AB, perpendicular to AB and F itself. What do the sides of the triangle represent? And what can you conclude from that?