Students will investigate relationships between perpendicular lines.
Question: How can one tell if two lines are perpendicular by only look at the equations of two given lines?

1. Familiarize yourself with the technology. Consider the following questions:
What type of lines is visible on the screen?
Use the pointer to move Point A or Point B. What do you notice?
What are the red triangles drawn next to the lines representing?
What do the letters c and d represent?
On the left side of the screen there is information listed.
What information is listed?
How does the information relate to the picture on the screen?
To the right is listed the “Slope of line 1” and “Slope of line 2”.
Which is line 1 and which is line 2? How do you know?
2. Exploration
List the equations of 3 sets of perpendicular lines. What do you notice?
How can you determine if two lines are perpendicular by ONLY looking at the equations of the lines?
If given two points on a coordinate grid, how would you find the equation of the line perpendicular through the line created by the two given points.