A circle C has centre D and equation
x² + y² + 2x – 8y + 8 = 0.
(a) Find the coordinates of D and the radius of C. 
(b) A line is drawn through the point P (4, 6) so that it touches the circle C at the point T.
(i) Show that PT = √20.
(ii) Find the equation of the circle centre P which passes through the point T. 
I know that a] will give D (-1, 4) and a radius of 3
But I have difficulty finding b and c. Can someone please help? I am having a lot of trouble with this and really need a bit of guidance.
Any help is appreciated