What is an obtuse angle?

An obtuse angle is defined as an angle that measures greater than 90 degrees and less than 180 degrees. This characterization is critical in geometry because angles are classified based on their measures, and understanding these classifications helps in solving various geometric problems.

To visualize this, consider a straight angle, which measures exactly 180 degrees, and a right angle, which measures exactly 90 degrees. An obtuse angle, being between these two values, will always open more than a right angle but will not reach the straight angle. This distinction not only identifies the angle as obtuse but also places it within a broader context of angular measurement, allowing students to better understand relationships between different types of angles.

This definition supports the identification of angles in various geometric shapes and can be pivotal in construction and design as well as in more advanced mathematical concepts.