An "elbow connector" in MS-Word is a 3-segment line with a control point in the middle as shown[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/Wcdco.jpg

where if I move the yellow control point sideways, then the length of the two lines on either side change accordingly while the end points remain the same. (Please ignore the "2" in the picture)

I am trying to understand how this works so that I can re-create this. Is there a "line equation" for such a line? How would I go about re-creating this?