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diff --git a/math/trisecare_pagina.tex b/math/trisecare_pagina.tex
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+\documentclass{standalone}
+%
+\usepackage{tikz}
+\usepackage{xcolor}
+%
+\definecolor{craterm}{HTML}{616060}
+%
+\title{Trisecare un foglio di carta}
+\begin{document}
+	\begin{tikzpicture}
+		\begin{scope}[scale=2]
+			\draw [thick] (2,0) rectangle (6,6);
+			\fill [blue, opacity=0.5] (2,0) rectangle (6,6);
+			\foreach \y in {0,2,4,6}
+				\draw [-,dashed] (0,\y) -- (8,\y);
+			\foreach \x in {2,3,...,6}{
+				\draw [-,dashed] (\x,0) -- (\x,6);
+				\fill [black] (\x,0) circle (0.05cm);
+			}
+			\fill [black] (4,2) circle (0.05cm);
+			\fill [black] (3,4) circle (0.05cm);
+			\fill [black] (2,6) circle (0.05cm);
+			\fill [black] (6,6) circle (0.05cm);
+			\draw [-,dashed] (2,6) -- (5,0);
+			%
+			\node [below=5] at (2,0) {$A$};
+			\node [below=5] at (6,0) {$B$};
+			\node [above=6,right] at (6,6) {$C$};
+			\node [above=6,left] at (2,6) {$D$};
+			\node [below=5] at (4,0) {$E$};
+			\node [below=5] at (5,0) {$F$};
+			\node [below=5] at (3,0) {$G$};
+			\node [above=6,right] at (3,4) {$H$};
+			\node [above=6,right] at (4,2) {$I$};
+		\end{scope}
+	\end{tikzpicture}
+\end{document}
\ No newline at end of file