1. Lines: Slope
The slope of a line is the ratio of the vertical change to the horizontal change between any two points on the line.
As a formula, slope = m =
Here, (x1, y1) and (x2, y2) are two points on the line.
Example 1: Find the slope of the line that contains the points (- 5, 3) and (4, 0).
Here, x1 = - 5, y1 = 3, x2 = 4, and y2 = 0.

2. Geometric Interpretation of slope: In example 1, means the
Lines: Slope
Geometric Interpretation of slope:
In example 1, means the
line falls (because of the negative) 1 unit for every three units to the right as shown by the red arrows on the graph.
Example 2: Find the slope of the line that contains the points (- 1, 3) and (- 1, - 2).
which is undefined.
Slide 2

3. Facts About Special Lines
Lines: Slope
In example two, the slope was found to be undefined Here the two points lie on a vertical line.
Facts About Special Lines
The slope of a vertical line is undefined.
The slope of a horizontal line is zero.
Parallel lines have the same slope.
Perpendicular lines slopes that are opposite in sign and reciprocals of each other.
Slide 3

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Lines: Slope
END OF PRESENTATION
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