[oasisbob]

Yes, and no. Trigonometry works if trees grow with a habit which matches the assumptions of a right triangle.

Before laser rangefinders were cheap and accessible, the method used (angle and an approximation of horizontal distance) would often grossly overestimate the height of the tree.

The modern sine method is much better, but still had problems with leaning trees, and will tend to underestimate height.

The most reliable method is to get someone up there and do a tape drop.

https://www.nativetreesociety.org/measure/tree_measuring_gui...

[thesausageking]

Seems like a great job for a drone.