Question 900624
{{{drawing(300,400,-1,2,-1,3, graph(300,400,-1,2,-1,3), circle(.5,1,sqrt(5/4)))}}}


{{{x^2+y^2+Dx+Ey+F=0}}}
<pre>
Substitute (0,0)

{{{0^2+0^2+D*0+E*0+F=0}}}

Substitute F=0

{{{x^2+y^2+Dx+Ey=0}}}

Substitute (1,0)

{{{1^2+0^2+D*1+E*0=0}}}

{{{1+D=0}}}

{{{D=-1}}}

Substitute D=-1

{{{x^2+y^2-x+Ey=0}}}

Substitute (0,2)

{{{0^2+2^2-0+E*2=0}}}

{{{4+2E=0}}}

{{{2E=-4}}}

{{{E=-2}}}

Substituting E=-2

{{{x^2+y^2-x-2y=0}}}  aka {{{(x-1/2)^2+(y-1)^2=5/4}}}

Edwin</pre>