Hey guys, I hope someone can give me some pointers with this because it should be really easy but im just not getting it! I want to show that for a triangle inscribedin a circle an equilateral traingle gives the maximal perimeter. Ive tried a few things and just get bogged down in algebra and im sure there should be a clean geometric proof! For example if you take a unit circle on the origin then I can set one of my points at the north pole (0,1), then in polars assign the other 2 points at B and C. But this gives me the problem of maximising 2sin(C/2) + 2sin(B/2) + sqrt(2-2cos(C-B)) which is very messy... can anyone give me some pointers? Thank you!