Talk:Stewart's theorem

Error in Proof

The proof as given, presumably taken from Cut-the-knot, is incorrect in that it assumes that the altitude falls on the opposite side, but this will not be the case if one of the angles at the base is obtuse. The same error was found in several other sources I found for the theorem. It can be easily fixed by splitting into cases but it seems simpler to use the law of cosines to prove the theorem, as is done on the PlanetMath page. Cut-the-knot also states incorrectly that the theorem was not proved by Stewart, though the proof he gives is somewhat convoluted.--RDBury (talk) 19:36, 31 January 2010 (UTC)[reply]

The proof has been rewritten according to the PlanetMath page.--RDBury (talk) 00:45, 21 July 2010 (UTC)[reply]