7 The equation of a straight line \(l\) is
$$\mathbf { r } = \left( \begin{array} { l }
1
0
2
\end{array} \right) + t \left( \begin{array} { r }
1
- 1
0
\end{array} \right) .$$
\(O\) is the origin.
- Find the position vector of the point \(P\) on \(l\) such that \(O P\) is perpendicular to \(l\).
- A point \(Q\) on \(l\) is such that the length of \(O Q\) is 3 units. Find the two possible position vectors of \(Q\). [3]