1. The problem statement, all variables and given/known data We consider Rectangle Parallelepiped on a board and a=1m ; b=2m and c=3m. The face a and b is considered touching the board. there’s no sliding; we tilt the board so a is horizontal. Q: Starting from which angle we can see a rotation? 2. Relevant equations I want to know how am I supposed to know how to find the angle precisely! 3. The attempt at a solution Sorry I'm not native English speaker, I translated my thing to here. I suck at Physics so I don't really even know where to begin with. I tried so many things, I've been staring at this for hours. It was supposed to be a chapter about moment of force but maybe I missed something the only formula I have about it is moment of force=Force * Distance :/ Help!