A circle can be drawn with any center and any radius

We can see a circle in blue color with center A. Coordinates of the center A are (x_1,y_1) and radius of the circle is r. We can change the values of x_1,y_1 and r using their respective slide bars. Let us change the values of x_1,y_1 and r and observe how the position and size of the circle changes. Equation of the circle ‘c’ that is (x – x1)2 + (y – y1)2 = r 2 is also mentioned in blue color along the circle.
Question/s to think about. Fix the values of x_1 and y_1 and change the value of r, what do we see? Fix the value of r and change the values of〖 x〗_1 and y_1, what do we see? How many circles do we get when values of x_1,y_1 and r are fixed?