Trigonometry has a lot of different identities. Trigonometry has been used in geodesy, surveying, celestial mechanics, and navigation throughout history. The Greeks concentrated on chord calculations, whereas Indian mathematicians developed the first tables of values for trigonometric ratios (also known as trigonometric functions) as a sine. Applications of geometry to astronomical research gave rise to the discipline in the Hellenistic culture during the 3rd century BC. The word trigonometry is made by the Greek word trigonon, 'triangle,' and metron, 'measure'. Trigonometry is a field of mathematics concerned with the connections between triangle side lengths and angles.
