7 The line with equation \(3 x + 4 y - 10 = 0\) passes through point \(A ( 2,1 )\) and point \(B ( 10 , k )\).
- Find the value of \(k\).
- Calculate the length of \(A B\).
A circle has equation \(( x - 6 ) ^ { 2 } + ( y + 2 ) ^ { 2 } = 25\).
- Write down the coordinates of the centre and the radius of the circle.
- Verify that \(A B\) is a diameter of the circle.