Question 837813

If the center is ({{{h}}},{{{k}}}) and the radius is {{{r}}}, the 
equation is {{{(x-h)^2+(y-k)^2 = r^2}}}

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so, if the center is ({{{0}}},{{{0}}}) and the radius is {{{5}}}, your equation is
{{{(x-0)^2+(y-0)^2 = 5^2}}}

{{{x^2 + y^2 =25}}}


{{{ graph( 600, 600, -10, 10, -10, 10, sqrt(-x^2+25),- sqrt(-x^2+25)) }}}