Summary
With the help of this activity, we have learnt that:
1. The slope of a line is 0 when the line is horizontal.
2. The slope of the line is undefined when the line is vertical.
3. When the two lines are parallel, the slopes are equal.
4. When the slopes are equal, the two lines are parallel.
5. When the product of two slopes is -1, then the two lines are perpendicular.
6. When the two lines are perpendicular, the product of the slopes is -1.
