If the determinant \(\left| {\begin{array}{*{20}{c}} {\cos 2 {\rm{x}}}\\ {{{\sin }^2}{\rm{x}}}\\ {\cos 2{\rm{x}}} \end{array}\begin{array}{*{20}{c}} {{{\sin }^2}x}\\ {\cos 2x}\\ {{{\cos }^2}x} \end{array}\begin{array}{*{20}{c}} {\cos 2x}\\ {{{\cos }^2}x}\\ {\cos 2x} \end{array}} \right|\) is expanded in powers of cos x, then the constant term in the expansion is