# 19 October 2020

## Detection of perpendicular lines in GeoGebra Discovery

In this new update of GeoGebra Discovery you can discover perpendicularities in a given planar figure. I decided to add this feature as soon as possible to support secondary school experiments, including the discovery of Thales' circle theorem.

Now… (you may need to click OK first on the applet below…)
1. Click on the Discover tool.
2. Select a point, say $$D$$.
3. The list of found properties should be shown in a popup window.
This new version has been released today.

## A further example

See also a filtered list of the entries on topics GeoGebra, technical developments or internal references in the Bible.

 Zoltán Kovács Linzer Zentrum für Mathematik Didaktik Johannes Kepler Universität Altenberger Strasse 54 A-4040 Linz