Imagine you had a triangular wooden painting that measured 300x400x250mm on the sides. You don't know the angles. You have some framing wood with a deep 24mm rebate. You need to know what length the wood needs to be on the internal edge, and at what angle to cut the ends too. Quite a conundrum!
I'm faced with just that (well, apart from those specific sizes) for the painting below so I've written a small program in Visual Basic to solve the riddle. One day I'll probably adapt it so that I can cut the angles for any quadrilateral... just in case!
Thanks to the internet I managed to program this without actual mathematical knowledge. Phew. I can't ever recall hearing of the law of cosines before but now I have.
Alas I don't have a mitre saw so I'll have to saw the angles by hand. Awkward, but possible. I've done it before and the results weren't that bad.
