If →a=→i+2→j+3→k,→b=2→i+3→j+→k,→c=3→i+→j+2→k and α→a+β→b+γ→c=−3(ˆi−ˆk), then the order triplet (α,β,γ) is
A unit vector coplanar with →i+→j+3→k and →i+3→j+→k and perpendicular to →i+→j+→k is