Ontario Mathematics Proficiency Practice Test

An acute angle is defined as an angle that measures less than 90 degrees. This means that any angle that falls within the range of 0 to just below 90 degrees qualifies as acute. The understanding of angle types is essential in geometry, where angles are categorized based on their measure.

For instance, less than 45 degrees encompasses a smaller subset of acute angles but does not define the full range, which is why specifying less than 90 degrees is the correct definition. Angles greater than 90 degrees are classified as obtuse angles, and angles equal to 90 degrees are defined as right angles. Thus, focusing on less than 90 degrees accurately captures all acute angles.