If \(\cos \left( {\frac{\pi }{4} - x} \right)\cos \,2x + \sin \,x\,\sin 2x\,\sec x = \cos x\sin 2x\sec x + \cos \left( {\frac{\pi }{4} + x} \right)\cos 2x\), then a possible value of sec x is
1
\(\frac{1}{2\sqrt2}\)
2
\(3\sqrt2\)
3
\(\frac{1}{\sqrt2}\)
4
\(\sqrt2\)