How do you identify the center and the radius of the circle with equation $x^2 + (y - 5)^2= 9$ ?

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Answer 1 · 2016-10-21T23:45:23

Please see the explanation.

If you write it in this form:

$(x - 0)^2 + (y - 5)^2 = 3^2$

And then compare it with the standard form:

$(x - h)^2 + (y - k)^2 = r^2$

where $(h,k)$ is the center and $r$ is the radius.

It is easy to observe that the center is $(0,5)$ and the radius is $3$ .

How do you identify the center and the radius of the circle with equation x^2 + (y - 5)^2= 9x^2 + (y - 5)^2= 9?