Drag around the A point first and then the B point to answer some questions about the ratios of coordinates to radius.
Move point A to coordinate (1,2) and coordinate B to (3,6). What is the radius of the circle through A? What is the radius of the circle through B? What is the ratio of the x coordinate divided by the radius for coordinate A? What is the ratio of the x coordinate divided by the radius for coordinate A? What is the ratio of the x coordinate divided by the radius for coordinate B? Try other coordinates in each of the other four quadrants. Based on our observation what can you say about the ratio of the x coordinate to the radius for two (or more) points that both are on the same ray from the origin?