Resolve the force F into
a) a part perpendicular to AB and
b) a part parallel to BC
a dot b = ab*cos(θ)
The Attempt at a Solution
I attached my attempt in the .pdf file. For some reason it is wrong. I don't understand how my reasoning is incorrect.
The orange square in the picture is a supposed to be a wooden box in the problem, so that detail is not important to the problem.