3. A circle \(C\) has equation
$$x ^ { 2 } + y ^ { 2 } - 6 x + 8 y - 75 = 0$$
- Write down the coordinates of the centre of \(C\), and calculate the radius of \(C\).
A second circle has centre at the point \(( 15,12 )\) and radius 10 .
- Sketch both circles on a single diagram and find the coordinates of the point where they touch.
(4)