Trigonometry means “triangle measure”. It is a branch of mathematics which was originally developed to calculate unknown sides and angles in triangles. Trigonometry is very useful in applications such as surveying, navigation and electronics.
Suppose you were a forester and you wanted to know the height of a tree without having to climb the tree with a measuring tape. You can find the height by taking two measurements from the ground (Figure 3).
Once the distance from the base of the tree is known, as well as the angular measurement to the top of the tree, you can make a scale drawing of a similar triangle and measure the length of the corresponding side (Figure 4).
Using the proportion:
the tree is 35.8 m tall.
By using trigonometry, you can solve problems like this in an even simpler fashion.