11.1 Measuring angles

Angles that should be recognizable include the 90° (right angle), 180° (straight line), 270° (reflex part of the right angle), and 360° (full revolution).

To measure acute angles such as 45°, we use a protractor. The 0° of the protractor is aligned with 1 line, and the other line is measured on the protractor.

Measuring an obtuse angle on a protractor is rather easy too, as most protractors have a 180° range. Same as supra.

To measure reflex angles, you should measure the acute version of the reflex angle (i.e. the opposite side), and then subtract that from 360°.