6. The minor axis of the ellipse $\rho=\frac{1}{2-\cos \theta}$ is equal to

保留了源文本的换行和格式。
6. $\frac{2}{3} \sqrt{3} \rho(0)=1, \rho(\pi)=\frac{1}{3}$, i.e., $a+c=1, a-c=\frac{1}{3}, 2 b=\frac{2}{3} \sqrt{3}$.