>Hi, i think my friend has found out how to trisect an angle.
>This is one of the "impossible"geometry problems. What
>should i do?

Keep cool head and do some reading. The problem is only "impossible" in general by compass and straightedge. With other implements it's quite possible. If your friend claims to have solved the Impossible One, do not bother. Recommend your friend a nice book by Underwood Dudley, The Trisectors.

http://www.amazon.com/exec/obidos/ASIN/0883855143/qid%3D1031987449/sr%3D11-1/ref%3Dsr%5F11%5F1/002-0986050-2068804