\documentclass{article}
\usepackage{tikz,amsmath}

\begin{document}
Some text Some text Some text Some text Some text Some text Some text 
\begin{equation}
\begin{pmatrix}\ 
\begin{tikzpicture}
\filldraw[fill=orange,line width=1pt] (0,0) -- (5,0) -- (5,-5) -- cycle;
\draw[line width=1pt] (0,-1) -- (4,-5);
\end{tikzpicture}
\ \end{pmatrix}
\end{equation}
Some text Some text Some text Some text Some text Some text Some text 
\begin{equation}
\begin{pmatrix}\ 
\begin{tikzpicture}
\filldraw[fill=orange,line width=1pt] (0,0) -- (0,-1) -- (4,-5) -- (5,-5) -- (5,0) -- cycle;
\end{tikzpicture}
\ \end{pmatrix}
\end{equation}
Some text Some text Some text Some text Some text Some text Some text 
\end{document}