When I am working on a problem I never think about beauty. I only think about how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong.
Here are some math puzzles that I have found interesting, some I have solved, some I haven't.
Given the square EFGH with sides of length r and the circle segments HKJF, HLMF, EKLG and EJMG each with a radius of r and center at one of the corners. Hint, think about the problem in terms of the area's of the regions created by the square and arcs (see left figure).
The four parts of the top figure are moved around in the bottom figure. The partitions are exactly the same as those used above. From where does the hole
come?