M2_8_8_2_1
GeoGebra Construction:
8_2_1
Construct two lines l and m. Mark their point of intersection. Now move a point
on one line so that the line rotates while the other line stays fixed. Watch what happens
to the point of intersection as the lines pass the position at which they are parallel.
Explain how what you observe justifies the choice of just one ideal point on each line
even though the line has two ends.
Solution:
The lines intersect at point C. When I use the move tool to move the points of one line as the other remains finxed, the point of intersection disappears.