Vertical Angles: A Quick Exploration

Part 1: Use the protractor to measure angles 1 and 2 below.

What did you get for the measure of ? How about ?

Use the slider above to change the size of the angles. Measure angle 1 and angle 2. What did you get?

Part 2: Use the slider below to change the sizes of angles 1 and 2. Use the protractor to measure them both again.

and are said to be vertical angles. From your observations, what seems to be true about vertical angles?