%A4  plots the A4 paper rectangle, and its special property

s = 297/210;
printf('s / 1     = %.10f\n', s )
printf('1 / (s/2) = %.10f\n', 1 / (s/2) )

x = [0 s s 0 0];
y = [0 0 1 1 0];
u = [s/2 s/2];
v = [0 1];
plot(x,y,'b',u,v,'g--')
text(.38 * s,1.05,'s = 297/210 \approx \sqrt(2)')
text(.23 * s,-.05,'s / 2')
text(-.05,.5,'1')
axis equal
axis off
set(gcf,'color','white')
