What is a protractor used for?

A protractor is specifically designed to measure angles, making it an essential tool in various fields such as geometry, construction, and engineering. It provides a precise way to determine the degree of an angle by allowing users to align the base line with one side of the angle and read the measurement against the scale marked on the protractor. This capability is crucial for tasks that involve angle measurement and construction, as angles must often be accurate to ensure that structures are built correctly and function as intended.

The other options, while they reference tools that fulfill different functions, are not applicable to the purpose of a protractor. For example, instruments that measure volumes are typically volumetric flasks or calipers, those that calculate stress would involve mechanical or structural analysis tools, and devices for cutting materials include saws and knives. Understanding the unique function of the protractor as an angle-measuring device highlights its importance in both theoretical and practical applications.