\documentclass[12pt]{article}
\usepackage{tikz}
\usepackage{pgf}
\usepackage{calc}
\usepackage[active,pdftex,tightpage]{preview}
\PreviewEnvironment[]{tikzpicture}


\begin{document}
       \begin{tikzpicture}[scale=1,very thick] %a very thick-et talan ki akarod majd venni. Van thin, thick, very thick, ultra thick, stb.
		\def\pointsize{0.06}

		\draw (-5.1,0) -- (0,0);
		\draw (0,5) -- (0,-0.2);

		\draw[fill=blue] (0,0) circle (\pointsize);

		\def\b{3}
		\def\h{\b*1.4142135623}

		\draw[blue] (-\b,0) -- (-\b,\h) node[midway,right,black] {$c$};
		\draw[red] (-\b,\h) -- (-\b+\h/2,\h/2) node[midway,above right,black] {$b$};
		\draw[red] (-\b,\h) -- (-\b-\h/2,\h/2) node[midway,above left,black] {$b$};
		\draw[green] (-\b,0) -- (-\b+\h/2,\h/2);
		\draw[green] (-\b,0) -- (-\b-\h/2,\h/2);
		\draw[fill=blue] (-\b,0) circle (\pointsize);
		\draw[fill=red] (-\b+\h/2,\h/2) circle (\pointsize) node[below,black] {$p_2$};
		\draw[fill=red] (-\b-\h/2,\h/2) circle (\pointsize) node[below,black] {$p_1$};
        \end{tikzpicture}
\end{document}

