History-Based Deletion: The elements are removed via a history entry; this means deleting them at a specific point in time in the history.
A sketch is always calculated step by step in the history. This means that these delete commands are necessary when you initially need an element but no longer need it later on.
Example: In the following example, a circle is to be placed at the center of a rectangle or square. If you want to construct the center rather than calculate it, proceed as follows:
Draw lines to find the center.
Draw the circle through the intersection of the two lines.
The lines are no longer needed.
Set now to delete
delete item [Delete element]
a.
Alternatively, you could also mark the lines as cosmetic elements; on the other hand, the sketch looks "cleaner" without cosmetic elements. Furthermore, if you continue working on this sketch, the lines—once deleted—will no longer create intersections, which can sometimes be very helpful.
