3. In parametric form
Representing the circle parametrically is quite simple. Recall that for a circle centered at the origin, the pair of equations describe a circle of radius as varies from 0 to . If we want to move the center from the origin, all we have to do is add the appropriate constant to the and coordinates.
> plot([2+3*cos(theta),1+3*sin(theta),theta=0..2*Pi], scaling=constrained);