LaTeX.org

Hi ,

I want to fill one of two of this draw but I didn't find how to use \arcsin in calculations.

\documentclass[11pt]{article}
\usepackage{tikz}
\usetikzlibrary{calc}

\begin{document}
\begin{tikzpicture}
% \foreach \r in {0.8,1.6,...,8.4} \fill [color=gray!20](\arcsin(0.4)/\r):\right ...