**3.5 Slopes of Lines**

**Definitions:**

**Rise**- the difference in the y-values of two points on a line

**Run**- the difference in the x-values of two points on a line

**Slope**- the ratio of rise to run for a line. The equation for slope (m) is :

**Theorems:**

Parallel Lines Theorem- In a coordinate plane, two non-vertical line are parallel if and only if they have the same slope. Any 2 vertical lines are parallel

Parallel Lines Theorem

**Perpendicular Lines Theorem**- In a coordinate plane, two non-vertical lines are perpendicular if and only if he product of their slopes is -1. Vertical and horizontal lines are parallel

**Examples:**