How to Draw a Folded Sheet of Paper

​Maybe this is what you're looking for. You have to set the variable \y to the value that gives the best result. \y has to vary between \h and \l. If you want a smaller picture, divide all the coordinates by a scale factor.

\documentclass{article} \usepackage{tikz} \begin{document} \begin{tikzpicture} \pgfmathsetmacro\y{9.5} \pgfmathsetmacro\l{8.5} \pgfmathsetmacro\h{11} \pgfmathsetmacro\a{sqrt(\y*\y-\l*\l)} \pgfmathsetmacro\b{\y-\a} \pgfmathsetmacro\x{\y*(\y-\a)/\l} \draw (\l-\x,0)--(0,0)--(0,\h)--(\l,\h)--(\l,\y); \draw[dotted] (\l,\y)--(\l,0)--(\l-\x,0); \draw (\l-\x,0)--(0,\b)--(\l,\y)--cycle; \node[below] at(\l/2,0){$\l$}; \node[above] at(\l/2,\h){$\l$}; \node[left] at(0,\h/2){$\h$}; \node[right] at(\l,\h/2){$\h$}; \end{tikzpicture} \end{document}