Suppose you have a shape consisting of two perpendicular rods (the whole shape is a rigid body) which stands upright so the plane of the rods is perpendicular to the plane of the ground, and the hypotenuse of the resulting triangle is on the ground. Each leg is a massive rod, so the forces acting on this right triangle are the normal force at each vertex (pointing upwards) and the weight of each leg (pointing downwards). Also assume the legs are rods of uniform mass, so the weight acts on the center of gravity of each leg. We wish to find the normal force on each leg. Considering net force, we can find the sum of the normal forces as the sum of the weights of each leg. We can find more information by taking torques about the point of contact between the two rods.
My question is how do we take the torque about this point? Can I simply choose one of the rods as a lever arm and say that the torques along this level arm must cancel, or must find the torques from each rod and then say those torques cancel? If the first statement is true then so is the second, but the first statement is stronger than the second so it may not be true.
Also, how would things change if the the rods were not glued together so as to form a rigid body - for example, how would it change if the rods were hinged at the point of contact so as to allow movement at this point?
I know how to solve this problem. My wording was not clear but what I intended to find out was made apparent by the below answers anyways.