Tableau de variation

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\usepackage[frenchb]{babel}
\usepackage{tabularx}
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\usepackage{fp}
\usepackage[load-configurations = abbreviations]{siunitx}

\usepackage{pstricks-add}

\usepackage{tikz,tkz-tab}


\def\R{{\mathbb R}}
%\def\Q{{\mathbb Q}}
\def\Z{{\mathbb Z}}
%\def\D{{\mathbb D}}
\def\N{{\mathbb N}}
\def\C{{\mathbb C}}
\def\ev{évènement }
\def\evs{évènements }

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\fbox{\begin{minipage}[t]{\linewidth}%
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%mettre les maths en gras
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\theoremstyle{break}
\theorembodyfont{\upshape}
\newframedtheorem{Th}{Th\'eor\`eme}
\newframedtheorem{Cor}{Corollaire}

\newframedtheorem{Prop}{Propri\'et\'e}
\newtheorem{Rem}{Remarque}
\newtheorem{Not}{Notation}
\newtheorem*{Dem}{D\'emonstration}
%\theorembodyfont{\rmfamily}
%\newtheorem{Exo}{EXERCICE \no{}}
%\theorembodyfont{\small \sffamily}
\newtheorem{Ex}{Exemple}
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\newframedtheorem{Def}{D\'efinition}

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\pagestyle{fancy}
\lhead{Terminale S}
\rhead{2015-2016}
\chead{Chapitre 4 : cours}


\begin{document}
	\begin{tikzpicture}
	\tkzTab{$x$/1,$\cos '(x)$/1,$\cos (x)$/2}{$0$,$\pi$}{z,-,z}{+/$1$, -/$-1$}
	\tkzTabVal[draw]{1}{2}{0.5}{$\dfrac{\pi}{2}$}{$0$}
	\end{tikzpicture}
\end{document}