# Vertical Lines

- Author:
- GeoGebra Materials Team

You are able to move the line by clicking on and moving point J. Please answer the questions below.

(1.) Which axis is the red line crossing? At what point is the line crossing this axis?
(2.) Move the blue slider to 1, what is the name and coordinates of the point that appears?
(3.) Move the slider to 2,3, and 4, what are the names and coordinates of the points that appear? What do you notice about the coordinates of these points?
(4.) Using the answers from the above questions, make a guess as to what the equation of this line is. Move the slider to 5 to check your answer.
(5.) Put the slider at 4. Use point J to move the line along the axis. Stop at any point and write the coordinates of the point J along with the equation of this line. Check your answer by moving the slider to 5.
(5.) Use any combination of two points that lie on the line to find the slope using the slope formula (y_2-y_1)/(x_2-x_1). Form a conclusion about the equation of vertical lines and their slopes.