- The circle \(C\) has equation
$$x ^ { 2 } + y ^ { 2 } - 10 x + 4 y + 11 = 0$$
- Find
- the coordinates of the centre of \(C\),
- the exact radius of \(C\), giving your answer as a simplified surd.
The line \(l\) has equation \(y = 3 x + k\) where \(k\) is a constant.
Given that \(l\) is a tangent to \(C\),
- find the possible values of \(k\), giving your answers as simplified surds.