Which tool is essential for measuring angles in navigation?

The compass is an essential tool for measuring angles in navigation because it helps determine direction relative to the Earth's magnetic field. In land navigation, a compass is used to identify bearings and orient maps, which is crucial for successfully navigating from one location to another. It functions by allowing the user to gauge the angle between the direction they want to travel and the magnetic north, providing an accurate means of navigation that accounts for the curvature of the Earth and the magnetic variations that may occur.

While a ruler and a protractor are instruments that can be used for measuring distance and angles, respectively, their applications are more aligned with technical drawings or geometric calculations than practical navigation. Similarly, calipers are designed for precise measurement of dimensions of objects and are not relevant to navigation tasks. Therefore, the compass stands out as the primary tool specifically geared towards the needs and challenges faced in navigation scenarios.