1. The problem statement, all variables and given/known data A uniform rod AB of weight W rests in equilibrium with the end A in contact with a smooth vertical wall and the end B in contact with a smooth plane inclined at 45 to the wall. Find the reactions at A and B in terms of W. 2. Relevant equations The sum of the three forces equal zero. 3. The attempt at a solution Well having a look at the answer is W and √2W, it's obviously a square and the rod must be perpendicular to the inclined plane. So how could I know that it was perpendicular to the plane. What indicated that or how can I prove that assumption to myself?