Measuring Tree Height with Trigonometry - Classic Field Method #3056297 (License: Personal Use)

This vintage line drawing depicts a surveyor using a sighting instrument (likely a clinometer or transit) to measure the angle from eye level to the tree’s top (point A), while standing at a known horizontal distance (OD) from the tree base (B). By applying right-triangle trigonometry-specifically tangent of the measured angle-the height AB can be calculated as AD + DB, where DB is the observer’s eye height. The dashed lines illustrate the geometric relationships essential to the method.

Used in forestry, land surveying, and historical science education to demonstrate practical applications of trigonometry; ideal for articles on old-school measurement techniques, STEM history, or outdoor education resources.