[justify]In the following GeoGebra applet, follow the steps below: [br]-Select the [b]COMPASS tool (Window 5)[/b]. Then click on line segment  CD (represents the opening length of the compass) and then on the point [b]A[/b]. Then click on line segment  CD (represents the  opening length of the compass) and then on the point [b]B. [/b] [b][/b][br]-Select the [b]INTERSECT (Window 3)[/b] and mark the intersections [b]E[/b] and [b]F [/b]of the two circles.  [br]- Select the [b]SEGMENT tool (Window 4) [/b]and draw a line segment with endpoints[b] E [/b]and [b]F.[/b] [br]-[b] [/b]Select the INTERSECT [b]tool (Window 3)[/b] and mark the intersection of line segments [b]AB[/b] and [b]EF[/b]. Change the name of the point to [b]M.[/b] -[br]Select the [b]SHOW/HIDE OBJECT tool (Window 6)[/b] and hide the circles and the line segment [b]EF[/b], leaving only the line segment [b]AB[/b] and the point [b]M.[/b] [br][b]NOTE[/b]: you can hide the objects by clicking on it with the right button and choosing the option "Show object".[br]- Select the tool [b]DISTANCE OR LENGTH (Window 7)[/b] and click on [b]A[/b] and then on [b]M[/b]. Then click on [b]B[/b] and then on [b]M.[/b] What do you see? What is a “Midpoint”? Points [b]A[/b] and [b]B[/b] are said to be symmetric in relation[br]to point [b]M[/b], which is considered the center of symmetry. [br]- Select the tool [b]MOVE (Window 1)[/b] move point [b]A[/b] or [b]B.[/b] Observe.[/justify]