Question 1085304

 {{{x^2+ y^2=49 }}}

 {{{x^2+ y^2=7^2 }}}-> here you have a circle

compare to a standard formula {{{(x-h)^2+(y-k)^2=r^2}}} you can see that

{{{r=7}}}
{{{h=0}}}
{{{k=0}}}

so, you have a circle with center at origin and a radius equal to {{{7}}}

{{{ graph( 600, 600, -10, 10, -10, 10,  sqrt(-x^2+49),-sqrt(-x^2+49)) }}}