8. The line \(L\) passes through the points \(\mathrm { A } ( 1,2,3 )\) and \(\mathrm { B } ( 2,3,1 )\).
- Find the vector \(\mathbf { A B }\).
- Write down the vector equation of the line \(L\).
- The plane \(\Pi\) has equation \(x + 3 y - 2 z = 5\).
- Find the coordinates of the point of intersection of \(L\) and \(\Pi\).
- Find the acute angle between \(L\) and \(\Pi\).