1. The problem statement, all variables and given/known data Had the same problem as this threadstarter: https://www.physicsforums.com/showthread.php?t=109059 2. Relevant equations 3. The attempt at a solution I managed to find a ratio of tangents for the two angles. From there, it seems you're supposed to go "well tan(x) ≈ x for small angles so let's magically assume this is a small angle and go grab a donut". Why is the small angle approximation appropriate for this problem and how do I avoid getting stuck on similar problems in the future?