Introduction: What is trigonometry?

What is trigonometry (or ‘trig’ as it is sometimes called)? A clue lies in the first part of the word ‘trigonometry’. ‘Tri’ means three; as in tricycle (three wheels) and triangle (three angles and three sides). Trigonometry deals with the relationships between the angles and sides of triangles.

The word trigonometry comes from the Greek words for triangle (trigōnon) and measure (metron).

From about the year 150 A.D., Egyptians and Greeks used trigonometry to measure the distances between objects and places they could not measure directly. They even used it to measure the distances between stars and the circumference of the Earth. Trigonometry uses a technique called triangulation to measure distances.

Trigonometry has, therefore, always played a key part in navigation. Many of the modern applications of trigonometry still have to do with navigation. Modern satellite navigation systems still use trigonometry and triangulation to find the distances between landmarks.

Artist’s concept of a NAVSTAR Global Positioning System satellite, a space-based radio navigation network

Other fields that use trigonometry include acoustics, optics, financial market analysis, electronics, probability, statistics, biology, medical imaging, chemistry, cryptology, meteorology, oceanography, land surveying, architecture, phonetics, engineering, computer graphics, and game development, amongst many others.