In this activity, you will explore the slopes of lines that are parallel and perpendicular to a given line (in red). [br][br]1. Drag the two blue points to give you a red line.[br]2. Move point D as you wish; this will be the point that your second line goes through.[br]3. Click Show Parallel or Show Perpendicular options in the bottom right, as needed.

1. Plot the red line through the points (1,3) and (-2,4). What is the slope of the red line?[br][br]2. Move D to any point. Select "Show Parallel". What is the slope of the new line?[br][b][br]Unselect "Show Parallel"[br][/b][br]3. Move point D to another point of your choice. Again select "Show Parallel". What is the slope of the new line? [br][br]4. Repeat steps 2 and 3 for a few more movements of D. What do you notice about each of the slopes of the lines through D?

1. Now unselect parallel line.[br][br]2. Does your red line have a positive or negative slope? [br][br]3. Select "Show Perpendicular". What is the slope of the new line?[br][br][b]Unselect "Show Perpendicular"[/b][br][br]4. Move of your blue points so your red line has a different slope.[br][br]5.. Select "Show Perpendicular". What is the slope of the new line?[br][br][b]Unselect "Show Perpendicular"[/b][br][br]6. Repeat steps 4 and 5 for a few more movements of D. What do you notice about each of the slopes of the lines through D?[br][br]