1. The problem statement, all variables and given/known data why we need to consider 2 conditions , the beam curve downwards ( as in 11-3) and beam curve upwards ( as in 11-4) ? What's the difference between 2 cases ? I notice that in both cases , the author assume clockwise as positive here are the 3 consecutive pages of notes 2. Relevant equations 3. The attempt at a solution I think the second cases where the curve curve upwards is unnecessary because we can see that the curve curve downwards (U shape) in the first photos .