For what value of k is the matrix [\table 2 \cos 2 \theta , 2 \cos 2 \theta , 6 ; 1-2 \sin ^{2} \theta , 2 \cos ^{2} \theta-1 , 3 ; k , 2 k , 1 ] singular? [NDA-I 2022]

Correct Answer is : Any real value