Question

what is the radius of the circle shown by:

x^2+y^2-2x+6y+9=0

Answer 1

Group the x terms together and complete the square.
Group the y terms together and complete the square.
Put it in the form: (x-h)^2 + (y-k)^2 = r^2
where (h,k) is the center of the circle and r is the radius.

Answer 2

I got a radius of 1, is that correct? @ranga

Answer 3

x^2+y^2-2x+6y+9=0
(x^2 - 2x) + (y^2 + 6y) + 9 = 0
(x-1)^2 - 1 + (y+3)^2 - 9 + 9 = 0
(x-1)^2 + (y+3)^2 = 1

Yes, the radius is 1. Good job!