\begin{tikzpicture}[scale=0.5]
	\begin{pgfonlayer}{nodelayer}
		\node [style=bullet] (0) at (-3.25, 0) {};
		\node [style=bullet] (1) at (-1, 3.75) {};
		\node [style=bullet] (2) at (1.25, 0) {};
		\node [style=bullet small] (3) at (-2.5, 0.25) {};
		\node [style=bullet small] (4) at (0.5, 0.25) {};
% 		\node [style=none] (5) at (-3.75, -0.5) {$i$};
% 		\node [style=none] (6) at (-1, 4.5) {$k$};
% 		\node [style=none] (7) at (1.75, -0.5) {$j$};
		\node [style=none] (8) at (-1, 1.5) {$\theta$};
	\end{pgfonlayer}
	\begin{pgfonlayer}{edgelayer}
			\draw (0) to node [above left] {$a$} (1);
		\draw (1) to node [above right] {$b$} (2);
		\draw (2) to node [below] {$c$} (0);
		\draw [style=red 1] (3) to (4);
	\end{pgfonlayer}
\end{tikzpicture}
