is a mathematics branch that deals with function of angles,calculation, and application in real life. The word trigonometryoriginated from a Greek words trigonon and metron meaning triangleand to measure respectively. developed from the need tocalculate distances and angles in areas such as map making,surveying, astronomy, and artillery range finding. consists of six functions of an angle namely cosine (cos), sine(sin), tangent (tan), cosecant (csc), secant (sec), and cotangent(cot). All the six functions are related to a right triangle.Mathematicians use trigonometric functions to calculate unknownangles and distances in geometric figures. There are two branches oftrigonometry: plane trigonometry and spherical trigonometry. Planetrigonometry computes distances and angles in one plane whilespherical trigonometry compute distances and angles in two or moreplanes of three-dimensional space.

Someof the mathematicians who contributed in the field of trigonometryare Hipparchus, Claudius Ptolemaeus, Omar Khayyam, and Nasir Al-DinTusi. Hipparchus was a Greek geographer, astronomer, and amathematician during the Hellenistic era. He came up withtrigonometric table and some formulas to solve problems of sphericaltrigonometry (Rogersn.p).He was the first scientist to develop a consistent method to predictsolar eclipses through his lunar and solar theories. Some of hisother achievements in the field of trigonometry are the discovery ofprecession, invention of astrolabe and armillary sphere, andcompilation of star catalogue. Claudius Ptalemaeus was a Greekgeographer, astrologer, mathematician, and astronomer. He developedsome of the trigonometric circa. Omar Khayyam was a Persianmathematician, and he combined approximation theory with trigonometryto come up with a formula to solve algebraic equations usinggeometrical formulas. In addition, Nasir Al-Din, a Persianmathematician, listed the six discrete cases in sphericaltrigonometry of a right-angled triangle.

WorkCited

Rogers,Leo. "The History of – Part 1.”:*Nrich.maths.org*.Web. 18 Nov. 2014. <http://nrich.maths.org/6843>.