6 Circles \(C _ { 1 }\) and \(C _ { 2 }\) have equations
$$x ^ { 2 } + y ^ { 2 } + 6 x - 10 y + 18 = 0 \text { and } ( x - 9 ) ^ { 2 } + ( y + 4 ) ^ { 2 } - 64 = 0$$
respectively.
- Find the distance between the centres of the circles.
\(P\) and \(Q\) are points on \(C _ { 1 }\) and \(C _ { 2 }\) respectively. The distance between \(P\) and \(Q\) is denoted by \(d\). - Find the greatest and least possible values of \(d\).