Principle objective of this lecture is to present on Protractor Usage. To use a protractor to: measure acute and obtuse angles to the nearest degree; draw acute and obtuse angles to the nearest degree. Protractors usually have two sets of numbers going in opposite directions. A protractor usually has two scales, starting at zero at opposite ends. The animation shows how to use both scales. The two angles are vertical angles and this also verifies that vertical angles are congruent.