Question 860526
{{{r^2=x^2+y^2}}} so {{{r=5}}} translates into
{{{x^2+y^2=5^2}}} <--> {{{highlight(x^2+y^2=25)}}}
{{{drawing(400,400,-6,6,-6,6,
grid(0),red(circle(0,0,5)),
green(line(0,0,4,3)),
locate(2,1.5,green(5))
)}}}