1. The problem statement, all variables and given/known data Find the acute angle between two diagonals of a cube. 2. Relevant equations N/A 3. The attempt at a solution I know that the length of a diagonal of a cube whose side lengths are each one is sqrt(3), so I think it has something to do with that. Other than that, I'm drawing a blank. I could use the unit vectors <1,0,0> and <0,1,0> and find the angle between them, but that's not giving me the right answer.