Measure an Angle with a Protractor Measuring an Angle Protractor is a geometrical instrument that looks like the letter D. The angles are marked from 0° to 180° on the edge in clockwise direction as well as in anti-clockwise direction. O is the midpoint at the baseline of the protractor.Let us measure angle ∠ABC and ∠PQR. Place the protractor in such a way that the … [Read more...] about How to Measure an Angle with a Protractor