documentclass{standalone}
%documentclass{amsart}
usepackage{mathtools}
usepackage{tikz}
usetikzlibrary{positioning}

begin{document}

begin{tikzpicture}[baseline=(current bounding box.north)]

draw [ultra thick, line width=0.70mm, black, fill=white] (-1.0,0) -- (0.0,0) arc(0:180:1.0) --cycle;
%
draw [ultra thick, line width=0.70mm, black, fill=white] (-1.0,0) -- (0.0,0) arc(0:180:1.0) --cycle;
draw [ultra thick, line width=0.70mm, black] (-1,0) -- (0,);
end{tikzpicture}

end{document}