Update
Sadly, this solution no longer works (as of TeX Live 2015). In the change history of minitoc
:
2015/07/13
- Jean-Pierre F. Drucbert passed away in 2009. So this package is now
looking for a maintainer.
- Reduce size of documentation, by
eliminating flags and other images, from 25+mb to less than 2mb.
You can retrieve the original version of the documentation from the TeXLive historic archive here.
Original answer
The astonishingly bizarre documentation for the minitoc
package has done most of the work for you. (Although with .png
images.) So for any flag you can think of the following will work: (You can also find maps as well.)
\documentclass{article}
\usepackage{graphicx}
% change the year to match your current distribution up to 2014
\graphicspath{{/usr/local/texlive/2010/texmf-dist/doc/latex/minitoc/}}
\begin{document}
\includegraphics[width=.3\textwidth]{brazil-f}
\includegraphics[width=.3\textwidth]{vanuatu-f}
\includegraphics[width=.3\textwidth]{belarus-f}
\end{document}
Just for entertainment, here are the flags of Brazil, Vanuatu, and Belarus.

Since adequate answers have already been given, I've felt free to do this picture with MetaPost.
For me it was an occasion to use some recent features of the luamplib
package, (which gives an interface to MetaPost in LuaLaTeX). More precisely, I've made use of the px
unit (which I didn't know of) thanks to the \mpdim
command, and of the integration of colors defined by the xcolor
package, via the \mpcolor
command.
The rectangle's dimensions follow the OP's first wishes, except for the star, for which it seems that several points are missing. So I've included a star of my own.
Edit I've made some minor changes, for the flag to be more like Burkina-Faso's official one, the way Paul Gaborit reports in its comment on the OP's question. So the red and green parts are reversed, and the star diameter is exactly one-third of the flag's height.
\documentclass{standalone}
\usepackage{luamplib, xcolor}
\definecolor{grun}{HTML}{239D48}%green - colour of the top rectangle
\definecolor{rot}{HTML}{BF0028}%red - colour of the bottom rectangle
\definecolor{gelb}{HTML}{F6eC0F}%yellow - colour of the star
\begin{document}
\begin{mplibcode}
u := \mpdim{1px}; % Unit length
beginfig(1);
z = u*(450, 300); path rect; rect = unitsquare xscaled x yscaled .5y;
% Star summits (I was not able to use the OP's given coordinates)
pair S[]; S0 = y/6*right rotated 18;
for i = 2 step 2 until 8: S[i] := S[i-2] rotated 72; endfor
for i = 1 step 2 until 9:
S[i] = whatever[S[(i-3) mod 10], S[(i+1) mod 10]] = whatever[S[i-1], S[(i+3) mod 10]];
endfor
% Drawings
fill rect withcolor \mpcolor{grun};
fill rect shifted (0, .5y) withcolor \mpcolor{rot};
fill S0 for i = 1 upto 9: -- S[i] endfor -- cycle shifted .5z withcolor \mpcolor{gelb};
endfig;
\end{mplibcode}
\end{document}

Best Answer
With no downloading:
See Is there a collection of national flags in TikZ? for the original question.