Find the center (h, k) and radius r of the circle with the given equation.
-$$x ^ { 2 } + y ^ { 2 } = 9$$
A) $( h , k ) = ( 0,0 ) ; r = 3$
B) $( \mathrm { h } , \mathrm { k } ) = ( 3,3 ) ; \mathrm { r } = 3$
C) $( h , k ) = ( 3,3 ) ; r = 9$
D) $( h , k ) = ( 0,0 ) ; r = 9$

Question

Quizplus · Accepted Answer

The equation of a circle in standard form is $(x - h)^2 + (y - k)^2 = r^2$, where $(h, k)$ is the center and $r$ is the radius. The given equation $x^2 + y^2 = 9$ matches this form with $h = 0$, $k = 0$, and $r^2 = 9$, which means $r = 3$.

Find the Center (H, K) and Radius R of the Circle