LaTeX-examples/tikz/pie-chart/pie-chart.tex

\documentclass[varwidth=true, border=2pt]{standalone}

\usepackage{pgf-pie}

\begin{document}
\begin{tikzpicture}
    \pie{10/A, 20/B, 30/C, 40/D}
\end{tikzpicture}
\end{document}