Does anybody know how to draw the right vertical line parallel to the left vertical line?
CODE:
\documentclass{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\draw[step=1ex,black!10,thin] (-4ex,-20ex) grid (15ex,50ex);
\draw (0ex,0ex) arc [start angle=135, end angle=405, radius=6ex] -- (7ex,50ex) -- (0ex,50ex) -- (0ex,0ex);
\end{tikzpicture}
\end{document}
OUTPUT:

