In each of the following, find the centre and radius of the circles.
x2 + y2 – 8x + 10y – 12 = 0
The equation of the given circle is x2 + y2 -8x + 10y -12 =0.
x2 + y2 -8x + 10y -12 =0
(x2 – 8x) + (y2+10y) = 12
+ 
– 16 – 25 = 12
(x - 4)2 + (y + 5)2 =53
(x - 4)2 + 
=
, which is form (x-h)2 +(y-k)2 = r2, where h=4,
K= -5 and r=
9