Constructing a Perpendicular Bisectors

After angle bisectors, the next thing you need to know are perpendicular bisectors, a.k.a line segment bisectors.

What is a perpendicular bisector?
A perpendicular bisector is a line which divides a line segment into two equal parts. This line is forms 2 right angles and is perpendicular to the line segment, thus giving rise to the name.

Note: the bisector of a line is of equidistant from the two points.

How to construct a perpendicular bisector?
I feel that describing it to you only makes you more complicated, so I shall leave the job to video and pictures.







As usual, it is important that the width of the compass doesn't change.

Credits:
http://upload.wikimedia.org/wikipedia/commons/4/45/Perpendicular_bisector.gif
http://www.youtube.com/watch?v=vmLpUrLSyIA
http://www.youtube.com/watch?v=cVozcIrgnP8