
\coordinate (S1) at ($(P)!1.5!(A1)$);
\coordinate (S2) at ($(P)!1.5!(A2)$);
\coordinate (Sk) at ($(P)!1.25!(Ak)$);

\coordinate (T1) at ($(P)!-0.6!(A1)$);
\coordinate (T2) at ($(P)!-0.7!(A2)$);
\coordinate (Tk) at ($(P)!-0.5!(Ak)$);


\draw []
   (T1)
   node [anchor=south west] {$s_1$}
   --
   (S1);


\draw []
   (T2)
   node [above] {$s_2$}
   --
   (S2);


\draw []
   (Tk)
   node [anchor=south east] {$s_m$}
   --
   (Sk);
