%AN EXAMPLE SHOWING THE INCLUSION OF A PICTEX FILE 
%YOU CAN GENERATE SUCH PICTURES, E.G., USING WINGEOM
\documentclass[12pt]{article}
\input epsf
\usepackage{pictexwd}

\begin{document}

What is the formula for the area of a spherical triangle $T$ on a
sphere
of radius $r$?
Suggestion:  Describe the triangle
as the intersection of three hemispheres
$A,B,C$, with angles between them being the angles of the triangle
itself, with measures $a,b,c$.

\begin{center}
\mbox{\input{vennsphere2.tex}}
\end{center}

\end{document}
