Perpendicular and Parallel Slopes

• The first line has Point C and Point D and is called Line CD.
• The second line has Point A and Point D and it is called Line AB.

• The graph bellow shows two parallel lines.
• Here you can drag around the points and both lines would stay parallel to each other.

• As you move around the points, what do you notice about the slope of Line CD and the slope of Line AB?

• Put Point A on (3,0).
• Put Point B on (5,3)
• Put point C on (-3,-3)

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• The graph bellow shows two perpendicular lines.
• Here you can drag around the points and both lines would stay perpendicular to each other.

• As you move around the points, what do you notice about the slope of Line CD and the slope of Line AB?

• Put Point A on (3,0).
• Put Point B on (5,3)
• Put point C on (-3,-3)

• Put Point A on (0,1).
• Leave Point B on (5,3)
• Leave point C on (-3,-3)

• Leave Point A on (0,1).
• Put Point B on (5,-5)
• Leave point C on (-3,-3)