First, you draw a rough picture. The slope of this straight line is certain. Now you put this straight line at a tangent position to the circle (at this time, only two points on the circle have a distance of 1 from the straight line), and then you translate it to the right until another tangent point. In the process of translation, you have experienced the process of having two points, three points, four points, three points and two points on the circle.

Then there can be four points between the three points, and then we can find them when the three points meet the conditions, and we can find them when we open the interval.

When there are three points, the distance from the straight line to the circle is 1. According to the distance between two straight lines, we can find out the tangent of the circle by using the radius from the origin to the straight line and the distance from (0 0) to the straight line as 1, and then continue to fall by using the tangent.

(I hope you understand)