\sigma_1:x(3\sqrt{18}-4\sqrt{77})-y(2\sqrt{18}-\sqrt{77})+ z(8\sqrt{18}-\sqrt{77})+2\sqrt{77}-\sqrt{18}=0\cr
\sigma_2:x(3\sqrt{18}+4\sqrt{77})-y(2\sqrt{18}+\sqrt{77})+ z(8\sqrt{18}+\sqrt{77})-2\sqrt{77}-\sqrt{18}=0