Hello, r_maths!

Welcome aboard!

Code:

* C
* |
A * * |
| * * |
| * * | 5
4 | * * |
| * θ * |
B * - - - - * - - - - - - * D
6 E 3 :

Two telephone poles, AB and CD, are situated 9m apart.

They are held by wires that are fixed to the ground at E.

Calculate exact value of

We want to find which is in

Look at the upper portion of the diagram. Code:

* C
| 1
A *-----------------------+ F
| 9 |
| |
4 | | 4
| |
B * - - - - + - - - - - - * D
6 E 3 :

Draw

We have a right triangle with

. . Hence: .

Back to the original diagram . . .

We have with

Using the Law of Cosines, we have:

. .

Therefore: .