Piecewise Function

\documentclass[12pt]{article}
\usepackage{pgf,tikz}
\usetikzlibrary{arrows}
\pagestyle{empty}
\begin{document}
\definecolor{uuuuuu}{rgb}{0.27,0.27,0.27}
\begin{tikzpicture}[line cap=round,line join=round,>=triangle 45,x=1.0cm,y=1.0cm]
\draw[->,color=black] (-1.66,0) -- (9.56,0);
\foreach \x in {-1.57,1.57,π,4.71,6.28,7.85,9.42}
\draw[shift={(\x,0)},color=black] (0pt,2pt) -- (0pt,-2pt) node[below] {\footnotesize $\x$};
\draw[color=black] (9.26,0.08) node [anchor=south west] { x};
\draw[->,color=black] (0,-1.36) -- (0,7.54);
\foreach \y in {-1,1,2,3,4,5,6,7}
\draw[shift={(0,\y)},color=black] (2pt,0pt) -- (-2pt,0pt) node[left] {\footnotesize $\y$};
\draw[color=black] (0.1,7.12) node [anchor=west] { y};
\draw[color=black] (0pt,-10pt) node[right] {\footnotesize $0$};
\clip(-1.66,-1.36) rectangle (9.56,7.54);
\draw plot[raw gnuplot, id=func3] function{set samples 100; set xrange [0.1:1.9]; plot cos((x*3.1415926535/2)*180/pi)+3};
\draw plot[raw gnuplot, id=func4] function{set samples 100; set xrange [3.1:4.9]; plot 1/(x-5)+5};
\draw plot[raw gnuplot, id=func5] function{set samples 100; set xrange [2.1:2.9]; plot -cos((x*3.1415926535/2)*180/pi)+3};
\begin{scriptsize}
\fill [color=uuuuuu] (0,4) circle (1.5pt);
\draw[color=uuuuuu] (0.14,4.28) node {$A$};
\fill [color=uuuuuu] (3,3) circle (1.5pt);
\draw[color=uuuuuu] (3.16,3.28) node {$B$};
\draw [color=uuuuuu] (2,2) circle (1.5pt);
\draw[color=uuuuuu] (2.16,2.28) node {$D$};
\draw [color=uuuuuu] (2,4) circle (1.5pt);
\draw[color=uuuuuu] (2.16,4.28) node {$E$};
\draw [color=uuuuuu] (3,4.5) circle (1.5pt);
\draw[color=uuuuuu] (3.14,4.78) node {$F$};
\end{scriptsize}
\end{tikzpicture}
\end{document}