A line can be taken as a circle with infinite radius and a circle can be assumed to be a polygon with infinite sides.
True
Draw an arc of smaller radius and join its ends at its centre. Now draw an arc of the bigger radius and try to join its ends at its centre, now draw a straight line and try to join its ends at its centre we can see that it will meet its centre at infinity, so from here we can conclude that a line is a circle of infinite radius.
Take a triangle and add it to another triangle it will form a quadrilateral, add another triangle to this quadrilateral it will form a pentagon, keep adding triangles to this polygon at one point you will realize that a polygon with infinite sides will be a circle, with each side being infinitesimally small.