1. The problem statement, all variables and given/known data Pls refer to the second photo , the red line part ....I don't understand the meaning of when 1 unit load move at C , the unit load is inclusive in the right system... I can understand the FBG sin45 + 1 = RE 2. Relevant equations 3. The attempt at a solution When the in unit load move at b , shouldn't the equation become like this ? FBG sin45 + 1 = RE Why the author didn't consider the unit load when the unit load is moved to B ?