7. The points \(P\) and \(Q\) have coordinates \(( - 2,6 )\) and \(( 4 , - 1 )\) respectively.
Given that \(P Q\) is a diameter of circle \(C\),
- find the coordinates of the centre of \(C\),
- show that \(C\) has the equation
$$x ^ { 2 } + y ^ { 2 } - 2 x - 5 y - 14 = 0 .$$
The point \(R\) has coordinates (2, 7).
- Show that \(R\) lies on \(C\) and hence, state the size of \(\angle P R Q\) in degrees.