Question 154246
{{{x^2+y^2-2x-4y-4=0}}}
{{{x^2+y^2-2x-4y=4}}}
{{{x^2-2x+y^2-4y=4}}}
{{{x^2-2x+1+y^2-4y+4=4+1+4}}}   (add 1 and 4 to both sides of the equation)
{{{(x^2-2x+1)+(y^2-4y+4)=9}}}
{{{(x-1)^2+(y-2)^2=3^2}}}
So
the center is (1,2),
the radius is 3
{{{graph(300,300,-10,10,-10,10,2+sqrt(8+2x-x^2),2-sqrt(8+2x-x^2))}}}