An acute angle is an angle that measures less than 90 degrees. It is one of the three basic types of angles, along with right angles and obtuse angles. Some examples of acute angles include 30 degrees, 45 degrees, and 60 degrees. Acute angles can be measured using a protractor. In real-life, examples of acute angles include the beak of a bird when it is open, a pair of open scissors, and the angle that is formed when a crocodiles mouth is open.