[list][*][size=200][/size]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.[/*][/list][list][*]The graph bellow shows two parallel lines.[/*][*][b]Here you can drag around the points and both lines would [i]stay [/i]parallel to each other[/b]. [/*][/list][list][*][b]As you move around the points[/b], [b]what do you notice about the [u]slope [/u]of Line CD and the slope of Line AB?[/b][/*][/list]
[list][*]Put Point A on (3,0).[/*][*]Put Point B on (5,3)[/*][*]Put point C on (-3,-3)[br][/*][/list]
[b]What is the slope of line AB?[/b]
[b]What is the slope of line CD?[/b]
[b]What is the rule for two lines to be parallel?[br][/b][list][*]In other words, what has to be true for the slope of Line AB and Line CD?[/*][/list]
[center][b][size=200]----------------------------------------------------------[/size][/b][/center]
[list][*]The graph bellow shows two perpendicular lines.[/*][*][b]Here you can drag around the points and both lines would [i][u]stay [/u][/i]perpendicular to each other.[/b] [/*][/list][list][*][b]As you move around the points, what do you notice about the [u][i]slope [/i][/u]of Line CD and the slope of Line AB?[/b][/*][/list]
[list][*]Put Point A on (3,0).[/*][*]Put Point B on (5,3)[/*][*]Put point C on (-3,-3)[br][/*][/list]
[b]What is the slope of line AB?[/b]
[b]What is the slope of line CD?[/b]
[list][*]Put Point A on (0,1).[/*][*]Leave Point B on (5,3)[/*][*]Leave point C on (-3,-3)[br][/*][/list]
[b]What is the slope of line AB?[/b]
[b]What is the slope of line CD?[/b]
[list][*]Leave Point A on (0,1).[/*][*]Put Point B on (5,-5)[/*][*]Leave point C on (-3,-3)[br][/*][/list]
[b]What is the slope of line AB?[/b]
[b]What is the slope of line CD?[/b]
[b]What is the rule for two lines to be perpendicular?[br][/b][list][*]In other words, what has to be true for the slope of Line AB and Line CD?[/*][*]Or, How do you think the slope of both lines are related?[/*][/list]