Question 946250
<pre>
{{{drawing(400,400,-4,10,-6,8, graph(400,400,-4,10,-6,8), circle(2,1,5),

green(line(2,1,5,5)),locate(2,1,"(2,1)"), locate(5,5.5,"(x,y)"), 



circle(2,1,0.15),circle(2,1,0.13),circle(2,1,0.11),circle(2,1,0.09),circle(2,1,0.07),circle(2,1,0.05),circle(2,1,0.03),circle(2,1,0.01),locate(3.5,3,5),

circle(5,5,0.15),circle(5,5,0.13),circle(5,5,0.11),circle(5,5,0.09),circle(5,5,0.07),circle(5,5,0.05),circle(5,5,0.03),circle(5,5,0.01)  )}}}{{{matrix(19,1,
Distance,from,arbitrary,point,"(x,y)",to,center,"(2,1)","",d=sqrt((x-3)^2+(y-1)^2),is,the,"radius=5","",
sqrt((x-2)^2+(y-1)^2)=5,(x-2)^2+(y-1)^2=5^2,x^2-4x+4+y^2-2y+1=25,x^2+y^2-4x-2y+5=25, x^2+y^2-4x-2y-20=0)


}}} 

Edwin</pre>