In \(△OAB\), \(O(0,0,0), A(6,2,-3)\) and \(B(4,0,3)\) are the vertices. Let \(\overset{⃗}{a}\) and \(\overset{⃗}{b}\) be position vectors of points \(A\) and \(B\) respectively and \(OM\) is the projection of \(\overset{⃗}{a}\) on \(\overset{⃗}{b}\) then \(l(AM)\) is equal to...