Let →a,→b and →c be unit vectors such that →a+→b−→c=0. If the area of triangle formed by vectors →a and →b is A, then what is the value of 4A2?
Let →a,→b,→c be three vectors such that |→a|=|→c|=1;|→b|=4 and |→b×→c|=√15. If →b−2→c=λ→a then a value of λ is