8. The points \(A\) and \(B\) have coordinates \(( 3,9 , - 7 )\) and \(( 13 , - 6 , - 2 )\) respectively.
- Find, in vector form, an equation for the line \(l\) which passes through \(A\) and \(B\).
- Show that the point \(C\) with coordinates \(( 9,0 , - 4 )\) lies on \(l\).
The point \(D\) is the point on \(l\) closest to the origin, \(O\).
- Find the coordinates of \(D\).
- Find the area of triangle \(O A B\) to 3 significant figures.