[Tex/LaTex] Tikz: Missing number, treated as zero

Question

After reading many related questions here about "Missing number, treated as zero", I still do not understand why the following example results in such an error message:

\documentclass[11pt]{article} 

\usepackage{tikz}
\begin{document}



\begin{figure}
\begin{tikzpicture}

\clip(2.5,-1.5) rectangle (6,2);
\draw(4+{sin(0)}, {cos(0)}) circle(4pt);

\end{tikzpicture}
\end{figure}

\end{document}

Answer 1

Change 4+{sin(0)} to {4+sin(0)}. The mathematics routines only apply to stuff inside curly brackets.