How do you find the center and radius of the circle #(x - 3) ^2 + (y + 1) ^2 = 9#?

1 Answer
Feb 5, 2016

Answer:

Center #(3, -1)#
#radius = 3#

Explanation:

The centre-radius form of a circle is #(x - h)^2 + (y - k)^2 = r^2# with the centre being #(h, k)# and #r# as the radius.

Given this, we would know that the center of the circle is #(3,-1)# and the radius is 3.

Luckily we are given the centre-radius form so we can easily get/compute for what was asked. However, if we are given the standard form of a circle, we should first do completing the square to transform it into its center-radius form.