Question 999352
{{{x^2+y^2=1 }}}....here you have a circle with center at origin and a radius {{{r=1}}}

 {{{drawing( 600, 600, -5, 5, -5, 5,
circle(0,0,.1),circle(0,0,1),circle(0,0,1),
 graph( 600, 600, -5, 5, -5, 5, 0)) }}}