Hello - My geometry is rusty and I'm having some difficulty visualizing a question. Picture a box sitting on an inclined plane with an incline angle of 30 degrees from the horizontal (floor). The box is at rest. There is a 10N normal force (perpendicular to horizontal) and a force, F, perpendicular to the plane itself. I'm looking for the setup. Is the angle formed between the normal force (10N) vector and the force (F) perpendicular to the incline the same as the angle at the angle of incline (30 degrees)? What are the rules for this in geometry - i.e. how can I tell where angles are congruent with relative ease? Thanks in advance.