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, (x 1, y 1 ) and (x 2, y 2 ) are two points on the line.

2. Lines: Slope Example 1: Find the slope of the line that contains the points (- 5, 3) and (4, 0). Here, x 1 = - 5, y 1 = 3, x 2 = 4, and y 2 = 0.

3. Lines: Slope Slide 2 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.

4. Lines: Slope Slide 2 Example 2: Find the slope of the line that contains the points (- 1, 3) and (- 1, - 2). which is undefined.

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

6. Lines: Slope