Trigonometry

By Prochazka, Helen | Australian Mathematics Teacher, Winter 2011 | Go to article overview

Trigonometry


Prochazka, Helen, Australian Mathematics Teacher


At first, trigonometry was associated with only the sides of a triangle. Thales (c. 624-546 BC) used triangles to find the height of a pyramid and to determine the distance of a ship from the shore with a method known as 'shadow reckoning'. The concept of a tangent developed from this technique.

For many centuries astronomy and trigonometry were interlinked. Many mathematicians considered themselves to be astronomers first. Mathematics and trigonometry in particular, was the principal tool they used for their astronomical calculations.

In about AD 150, the Greek mathematician and astronomer, Claudius Ptolemy (c. 90-168) published the Almagest. This 13-volume work deals with the motion and position of the stars and planets. It was used as a standard astronomy reference for more than a millennium, in the East and the West.

In Chapter 6 of Book 1, Ptolemy states that in relation to the distance of the fixed stars, the Earth was so small that it should be treated as a mathematical point.

The Almagest included the equivalent of a table of sine values. Today a scientific calculator will provide such data.

The Hindu mathematician and astronomer Aryabhata (476-550) collected and expanded upon earlier Hindu advances in trigonometry. …

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