1. A box sits on a horizontal wooden board. The coefficient of static friction between the box and the board is 0.22. You grab one end of the board and lift it up, keeping the other end of the board on the ground. What is the angle between the board and the horizontal direction when the box begins to slide down the board 2. Relevant equations µ = f / N 3. I do not understand how to calculate an angle when only one variable is given. I know how to calculate the angle when you're able to calculate the sides and then use the arc tan to solve for the angle. If someone could please explain how to work out this problem I would greatly appreciate it.