Which instrument is used to measure the heights of objects using trigonometry?

The clinometer is the instrument specifically designed for measuring the heights of objects using trigonometric principles. This tool operates by allowing the user to read angles of elevation or depression from a specific point to the top or bottom of an object, such as a tree or building. By applying basic trigonometry and knowing the distance from the clinometer to the object, one can accurately calculate the height of that object.

This application is particularly useful in forestry and environmental studies, where understanding tree height is crucial for assessing forest health, biomass, and ecological interactions. The clinometer typically features a sighting mechanism and a scale to indicate angles, making it a practical device for foresters, surveyors, and environmental scientists.

Other instruments mentioned serve different purposes. A barometer measures atmospheric pressure, an altimeter measures altitude based on air pressure, and a protractor is used to measure angles in two-dimensional geometry but does not provide a means of measuring height in relation to distance.