Move each point or adjust the x and y and it will make a circle that intersects the points. If the points are in a line, what happens? If the points are almost in a line, what happens? Answer 1: A single circle can not be made that intersects them. Answer 2: The intersecting circle is very big. It may not draw correctly.
Based on vlad_11's remix of Pi2345's Three Point Circle. Bug: If point 1 and point 2 align horizontally, point 3 is ignored. See dapontes' project for more on the same idea: http://scratch.mit.edu/projects/10803068/