Parallel Consequence? (VA)

The 2 lines shown below are PARALLEL LINES drawn within the coordinate plane. Interact with this applet for a few minutes. (Be sure to adjust the sliders.) Feel free to move the BIG WHITE POINTS anywhere you'd like as well. Then, answer the questions that follow.

What is the measure of the gray angle? How do you know this?

What can you conclude about any 2 non-vertical parallel lines drawn within the coordinate plane?