If the position vectors of points \(A\), \(B\), \(C\) and \(D\) are respectively \(\hat i+\hat j+\hat k\), \(2\hat i+5\hat j\), \(3\hat i+2\hat j-3\hat k\) and \(\hat i-6\hat j-\hat k\), then find the angle between the lines \(AB\) and \(CD\). Prove that \(AB\) and \(CD\) are collinear.