What is the radius of the circle shown below (and how did you solve it)? x^(2) + y^(2) -12x -6y +9=0

Question

What is the radius of the circle shown below (and how did you solve it)?


`x^(2) + y^(2) -12x -6y +9=0`

Answer 1

so you rearrange it as two separate equations to complete the square so
(x-6)^2 -36 + (y-3)^2 - 9 +9 = 0
then move the integers to the other side so its in the right format for the equation of a circle and root it
so radius is 6