Geometry 3.4 Big Idea: Find the Slope of a Line. Determine if lines are parallel or perpendicular.
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Transcript of Geometry 3.4 Big Idea: Find the Slope of a Line. Determine if lines are parallel or perpendicular.
Find the slope of a line that passes through(-1, 3) and (3, 2).
Find the slope of a line that passes through (-1, 1) and (2, 0).
Which line is steeper?
Postulate 17: Slopes of Parallel
LinesIn a coordinate plane,
two nonvertical lines are ║ if and only if they have the same slope. (Any 2 vertical lines are parallel.)
Postulate 18: Slopes of
Perpendicular LinesIn a coordinate plane, two
nonvertical lines are ┴ if and only if the product of their slopes is -1. (All horizontal lines are ┴ to all vertical lines.)
• Find the slope of the line that passes through (-1, 3) and (4, 1).
• Find the slope of the line that passes through (-2, -1) and (3, -3).
• Are these lines parallel or perpendicular?
• Find the slope of the line that passes through (2, 5) and (5, 3).
• Find the slope of the line that passes through (3, 0) and (7, 6).
• Are these lines parallel or perpendicular?
Graph• Graph the line through the given point with
the given slope.
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