Let ` vec a=a_1 hat i+a_2 hat j+a_2 hat k , vec b=b_1 hat i+a_2 hat j+b_2 hat k ,a n d vec c=c_1 hat i+c_2 hat j+c_2 hat k ,` be three non-zero vectors such that ` vec c` is a unit vector perpendicular to both vectors ` vec aa n d vec b` . If the angle between `aa n db` is `pi//6,` then `|a_1a_2a_3b_1b_2b_3c_1c_2c_3|^2` is equal to 0 1 `1/4(a1 2+a2 2+a3 2)(b1 2+b2 2+b3 2)` `3/4(a1 2+a2 2+a3 2)(b1 2+b2 2+b3 2)(c1 2+c2 2+c3 2)`