• Journal for History of Mathematics
• /
• v.20 no.4
• /
• pp.105-122
• /
• 2007

In this paper we analyze various studies on $Erd\ddot{o}s-Mordell$ inequality(from a point O inside a given triangle ABC the perpendiculars OP, OQ, OR are drawn to its sides, then OA+OB+OC${\ge}$2(OP+OQ+OR)). We find out three trends of studies on $Erd\ddot{o}s-Mordell$ inequality: studies on various proof methods, studies on related means, studies on $Erd\ddot{o}s-Mordell$ type inequalities.