Question 998849
{{{x^2+y^2-4y+4=100}}}......this is equation of a circle; so, standard formula is {{{(x-h)^2+(y-k)^2=r^2}}} where {{{h}}} and {{{k}}} are {{{x}}} and {{{y}}} coordinates of the center, and {{{r}}} is a radius

{{{x^2+(y^2-4y+4)=100}}}...complete square


{{{x^2+(y^2-4y+2^2)=100}}}

{{{x^2+(y-2)^2=100}}} or,

{{{(x-0)^2+(y-2)^2=100}}}

so, you have {{{h=0}}},{{{k=2}}}, and {{{r=10}}}

center: at ({{{0}}},{{{2}}})

{{{drawing( 600, 600, -15, 15, -15, 15,
circle(0,2,.2), locate(0.3,2,C(0,2)),
 graph( 600, 600, -15, 15, -15, 15, sqrt(100-x^2)+2,-sqrt(100-x^2)+2)) }}}