KöMaL 2011 B4325

$a$) Is the inequality $PA$+$PB$<$CA$+$CB$ true for all interior points $P$ of an arbitrary triangle ABC ? $b$) Is the inequality $PA$+$PB$+$PC$<$DA$+$DB$+$DC$ true for all interior points $P$ of an arbitrary tetrahedron ABCD ?