Copy of Investigating Line Segments
Hold down the shift key and click and drag on the window to move the axes. Hold down the shift key and scroll down/up to zoom in/out. In this application, you can move the points A, B, and C by clicking and dragging them. You can also turn the displayed distances on or off, or turn point B on or off.
 Place A, B, and C so that B is between A and C. What do you notice about the distances?  Place A, B and C so B is the midpoint of segment AC. How do you know that B is the actual midpoint?  Place A, B and C so B is between A and C and AB=BC. What do you notice about the figure?  Can you have AB=BC but not have B between A and C? If so, give the points. If not, why not?  Can you find the midpoint if we know the coordinates of the endpoints? How?  Can you find a missing endpoint if you know the midpoint and an endpoint? How?