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Trig Ratios Unplugged


Sine, Cosine and Tangent are the three main trigonometric or Trig Ratios. Before we look at these in more detail, where did these strange terms come from?

HipparchusTrigonometric functions were studied by Hipparchus of Nicaea (180–125 BC), Ptolemy of Egypt (90–165 AD), Aryabhata (476–550), Varahamihira, Brahmagupta, Ulugh Beg and others (14th century).Ulugh Beg

The word “sine” comes from the Sanskrit word for half the chord, jya-ardha, abbreviated to jiva. This was transliterated in Arabic as jiba, written jb, since vowels are not written in Arabic. Then this was mis-translated in the 12th century into Latin as sinus, which means “bay” or “fold”. Finally, English usage converted the Latin word sinus to sine.

“Cosine” was originally written “co.sine,” short for “COMPLEMENTI SINUS”
the sine of the complement.

“Tangent” comes from the Latin tangens, “to touch.” In other words, it means “touching.” The tangent of an angle uses the two sides of a triangle that touch the right angle.

This diagram explains how we use the three trig ratios:
TrigRatiosSlideBut, wait…there’s more. Check out this ppt which shows you how to use the Trig Ratios!Trig Ratios

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