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

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