9 A circle with centre \(C\) has equation \(x ^ { 2 } + y ^ { 2 } - 2 x + 10 y - 19 = 0\).
- Find the coordinates of \(C\) and the radius of the circle.
- Verify that the point \(( 7 , - 2 )\) lies on the circumference of the circle.
- Find the equation of the tangent to the circle at the point \(( 7 , - 2 )\), giving your answer in the form \(a x + b y + c = 0\), where \(a , b\) and \(c\) are integers.