Thanks to Rex Boggs, Rockhampton Grammar School, Australia (http://bit.ly/rexboggs) for help with the English translation.

Drawing and Naming Perpendicular Lines (using a triangle and ruler)

How do you draw perpendicular lines and perpendicular line segments on paper?
What is the symbol for "is perpendicular to"?
What is the symbol for "is not perpendicular to"?
Find the answers in this video.

Constructing Perpendicular Lines (using a straightedge and compass)

Did you know that we can draw perpendicular lines using just a straightedge
and a compass (without a set square)? In that case, we say that we construct
perpendicular lines.
To learn how to do it, watch this video. 1st part of the video:
For given line a and point T on this line, we construct line b
which is perpendicular to the line a and goes through point T. 2nd part:
For given line c and external point T, we construct line d
which goes through point T and is perpendicular to line c.

Drawing Perpendicular Lines in GeoGebra

In this video you can see how to draw perpendicular lines and
perpendicular line segments in GeoGebra (GGB) and how to write that they
are perpendicular.