If →a is a vector of magnitude 3 units, then ∣∣→a×^i∣∣2+∣∣→a×^j∣∣2+∣∣→a×^k∣∣2 is equal to
9
18
6
12
given expression =2|→a|2=18
A vector of magnitude √2 coplanar with the vectors →a=^i+^j+2^k and →b=^i+2^j+^k and perpendicular to the vector →c=^i+^j+^k, is