[tex3]\triangle APO (isósceles): AO ~é~ bissetriz ~de~ A ~e ~OP \parallel AC\\
D= OP\cap BC \implies \triangle ODC (isósceles) \implies 2p \triangle BPD = AB + BC = 20\\
(2p = BP+PO+PD+DB = 9-PA+PA+CD+11-CD = 20)\\
\therefore razão ~de~ semelhança \frac{2pBPD}{2pABC}=\frac{ 20}{36} = \frac{5}{9}\\
\therefore BP = \frac{5}{9} * AB = 5\\
BM = p\triangle ABC-b = 18 - 16 = 2 \\
\therefore \boxed{\color{red} PM = 5-2=3}[/tex3]
(Solução:sousóeu -
viewtopic.php?f=4&t=61425&p=163089&hili ... 11#p163089)