5 Two planes, \(\Pi _ { 1 }\) and \(\Pi _ { 2 }\), have equations \(3 x + 2 y + z = 4\) and \(2 x + y + z = 3\) respectively.
- Find the acute angle between \(\Pi _ { 1 }\) and \(\Pi _ { 2 }\).
The line \(L\) has equation \(x = 1 - y = 2 - z\).
- Show that \(L\) lies in both planes.