From GeoGebra Manual
- AreConcurrent( <Line>, <Line>, <Line> )
- Decides if the lines are concurrent. If the lines are parallel, they considered to have a common point in infinity, thus this command returns true in this case.
Normally this command computes the result numerically. This behavior can be changed by using the Prove command.
AreConcurrent(Line((1, 2), (3, 4)), Line((1, 2), (3, 5)), Line((1, 2), (3, 6)))yields true since all three lines contain the point (1,2).