Source: Parallel tracks, Jim Champion, Flickr

Remember, parallel lines are lines that never intersect, like the tracks in the sand.

Perpendicular lines intersect to form a right angle, like the architecture on this building.

Source: Day 243: Angles, Quinn Dombrowski, Flickr

We can see the see the characteristics of parallel and perpendicular lines by looking at their equations and graphs.

Below is an example of parallel lines on a graph.

Looking at the graph of these lines, we can see that they:

• are both linear
• both have a slope of 1/3; find the slope by reducing the fraction formed by putting the rise over the run
• the lines never intersect

We can verify the slope is the same by changing the equation from Standard Form to the Slope-Intercept Form.

Therefore, characteristics of parallel lines:

• linear
• same slope: in equation, on graph
• never intersect

Create a vocabulary entry for parallel lines in your notes. Add the characteristics you’ve identified.