I've only just started to study a degree in Mathematics and I find it extremely satisfying to have a seemingly easy question that is incredibly difficulty or tricky to work out. I've looked into heaps of competition exams (although they aren't really what I'm looking for - seeing that they don't usually seem easy). A good example are the so called 'Coffin Problems' (you can find some here).
I'm reaching out here to hear any original problems that fit into this category. Here's an example of mine:
If $\sin \theta + \cos \theta + \tan \theta = -1$, find the values of $\sin \theta + \cos \theta - \tan \theta$ for $\theta$ not being a multiple of $\pi$.
From memory, one of the answers I got for that problem was $\sqrt{2}-1$, although I know that there are plenty of other answers.
Also, I appologise if this question does not belong on this site. This was the only site I thought of to ask a question like this. Thanks!