# ### Example #1 ### Example #2 ## More Examples

### What happens to the slope of lines that are vertical and horizontal? Compute the slopes and put the calculations into the calculator and see what you get.

```    We call this "0 slope"                We call this "No slope"
(Notice, here we cannot
divide by 0!)```

### 6. Based on the results 4 and 5, what conclusion can you make about the slopes of perpendicular lines? Conclusions * If two lines are parallel, they have the same slope. * If two lines are perpendicular, the have a slope that is the negative reciprocal and their product is -1. Investigate the slopes above. Is this true? Use Geometer's Sketchpad to compute the slopes of the following points and find the slope of a line parallel and the slope of a line perpendicular to the given line. 1. A(6, 3) and B(4, 6) 2. C(-1, -5) and D(3, -2) 3. E(0, 5) and F(-1, 6) 4. G(-4, -2) and H(-5, -2) Now, using Algebra Xpresser to find 3 lines parallel to each other and 2 lines perpendicular through the parallel lines. Give each slope and two points that lie on each line.Day 4: Slope-Intercept Form of an Equation The standard form that equations are written in is called slope-intercept form of the line where y=mx + b. In this form, m represents the slope and b represents the y-intercept. The y-intercept is the point where the graph crosses the y axis. Find the slope and y-intercept of the following lines. Now, using Algebra Xpresser, graph the above lines.

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