Hello, SMA777!

This is a classic problem, found in every textbook.

Here is one approach to it . . .

Student has to find the height of tower some distance away

without leaving the campus. .They have angleometers, Code:

* C
* * |
* * |
* * |
* * | h
* * |
* * |
* α * β |
* - - - - - - - * - - - - - - - *
A 100 B x D

The tower is

The first observation is made at

The angle of elevation to the top of the tower is:

Moving 100 feet closer to the tower, another observation is made at

The angle of elevation to the top of the tower is:

Let

In right triangle .[1]

In right triangle .[2]

Equate [1] and [2]: .

. .

Therefore: .

We have found the height of the tower without leaving the campus.

. . In fact, we don't need to know the distance to the tower.