If the vectors vec(P) = a hat(i) + a hat(j) + 3 hat(k) and vec(Q) = a hat(i) - 2hat(j)- hat(k) are perpendicular to each other then the positive value of .a. is

If the vectors vec(P) = a hat(i) + a hat(j) + 3 hat(k) and vec(Q) = a

1.	If the vectors vec(P) = a hat(i) + a hat(j) + 3 hat(k) and vec(Q) = a hat(i) - 2hat(j)- hat(k) are perpendicular to each other then the positive value of .a. is
Answer» Zero 1 2 3 Answer :D