A normal vector to the circle x^2+y^2=1 at point (x,y) is (x,y), isn't it?
Having a circle, knowing its center and radius, how can I calculate the normal vector? I need more information? Moreover, how can I calculate a tangent vector to the circle, knowing its center, radius and the normal vector?
If I rotate this circle, it is possible to calculate again the normal vector with the same direction? Because the normal vector can be pointing in opposite directions.
Thank you very much for your help.