2. The position vectors of the points \(A , B , C , D\) are given by
\(\mathbf { a } = 2 \mathbf { i } + 3 \mathbf { j } - \mathbf { k }\),
\(\mathbf { b } = 4 \mathbf { j } + 5 \mathbf { k }\),
\(\mathbf { c } = 7 \mathbf { i } - 3 \mathbf { k }\),
\(\mathbf { d } = - 3 \mathbf { i } - \mathbf { j } - 5 \mathbf { k }\),
respectively.

1. Find the vector equations of the lines \(A B\) and \(C D\).
2. Determine whether or not the lines \(A B\) and \(C D\) are perpendicular.