A man 1.7 m tall observes a bird on top of a tree at an angle of elevation of 30∘. If the distance between the man's head and the bird is 25 m, what is the height of the tree?
Worked solution (try it first)
The 25 m from his head to the bird is the sloping line of sight, the hypotenuse.
The height of the bird above his head is opposite the 30∘ angle: 25sin30∘=12.5 m.