The drag effect
This activity belongs to the GeoGebra book Linkages.
Let's take a closer look at the EF bar from the previous activity. As we have pointed out, both points are free. The bar can be dragged independently. Moving E causes a script to drag F. Moving F causes a similar script to drag E.
Indeed, the behavior of the EF bar is the one that is most similar to the real behavior of a physical bar of length 1 unit. However, it is important to note that the position of E does not determine that of F, and vice versa.
At the start of this construction, point E occupies the same position as fixed point A, while F is placed one unit to the right of E. If we now walk point E around the screen a bit, dragging point F, and we end the walk again at point A, point F does not necessarily have to occupy the same position as it did initially.
Author of the construction of GeoGebra: Rafael Losada