1. The problem statement, all variables and given/known data 2. Relevant equations Trigonometric identities and differentiation 3. The attempt at a solution It's pretty simple to solve this question when the hallway is a right angle. Differentiating -6cscθ + 9secθ and setting it equal to zero and solving will yield the proper answer. But I don't know if the same method can be applied for this question? How would I start to solve this question?