Question

center and radius of the equation x^2+y^2=81

Answer 1

(x-h)^2 + (y-k)^2 = r^2
(h,k) is the center.
r is the radius.

Answer 2

@chrismae18 Hi,
\(\Huge \mathcal{\text{Welcome To OpenStudy}\ddot\smile} \)

The centre and radius of a standard circle \(\Large x^2+y^2 = r^2\)
will be Centre = (0,0) and radius = r

so what can you say about the radius of your circle ?

Answer 3

\[x^{2}+y^{2}=r^{2}\] The radius can be determined by \[\sqrt{x^{2}+y^{2}} =r\]