xbasc()
xsetech(frect=[-3,-3,3,3])
theta=[-%pi/6,%pi/2,%pi*7/6,-%pi/6];
T=[cos(theta);sin(theta)];
Ts=(1/(1+2*sin(%pi/6)))*rotate(T,%pi);
x=[T(1,:);Ts(1,:)]'; y=[T(2,:);Ts(2,:)]';
xset('thickness',4);
xpolys([x+cos(%pi/6),x-cos(%pi/6),x],[y+sin(%pi/6),y+sin(%pi/6),y+1+2*sin(%pi/6)]);