# History of trigonometric functions

Law of sines The law of sines states that for an arbitrary triangle with sides a, b, and c and angles opposite those sides A, B and C: This shows the main use of tangent and arctangent: There is a series representation as partial fraction expansion where just translated reciprocal functions are summed up, such that the poles of the cotangent function and the reciprocal functions match: Menelaus worked in Rome producing six books of tables of chords which have been lost but his work on spherics has survived and is the earliest known work on spherical trigonometry. Trigonometry, like other branches of mathematics, was not the work of any one man, or nation. Analogous formulas for the other functions can be found at Inverse trigonometric functions. The works of the Scottish mathematicians James Gregory in the 17th century and Colin Maclaurin in the 18th century were influential in the development of trigonometric series. It can be proven by dividing the triangle into two right ones and using the above definition of sine.

It also provides a single visual picture that encapsulates at once all the important triangles. Thus, in the first quadrant, where x and y coordinates are all positive, all six trigonometric functions have positive values.

The abbreviated symbol sin was first used in by Edmund Gunteran English minister and instrument maker. This theorem can be proven by dividing the triangle into two right ones and using the Pythagorean theorem.

Here, k is a constant that represents a mapping between units. The first major ancient work on trigonometry to reach Europe intact after the Dark Ages was the Almagest by Ptolemy c. He also gave the following approximation formula for sin xwhich had a relative error of less than 1.

Sine function sindefined as the ratio of the side opposite the angle to the hypotenuse. Once the angles are known, the ratios of the sides are determined, regardless of the overall size of the triangle. Influential works from the 4th—5th century, known as the Siddhantas of which there were five, the most complete survivor of which is the Surya Siddhanta  first defined the sine as the modern relationship between half an angle and half a chord, while also defining the cosine, versineand inverse sine. For example, the triangle contains an angle A, and the ratio of the side opposite to A and the side opposite to the right angle the hypotenuse is called the sine of A, or sin A; the other trigonometry functions are defined similarly. When the value of a trigonometric function is undefined, it means that the ratio for that given function involved division by zero.

For example, the triangle contains an angle A, and the ratio of the side opposite to A and the side opposite to the right angle the hypotenuse is called the sine of A, or sin A; the other trigonometry functions are defined similarly. Rheticus also produced substantial tables of sines and cosines which were published after his death.

On Triangles contains all the theorems needed to solve triangles, planar or spherical—although these theorems are expressed in verbal form, as symbolic algebra had yet to be invented. Their extension to nonperiodic functions played a key role in the development of quantum mechanics in the early years of the 20th century.

The thirteen books of the Almagest are the most influential and significant trigonometric work of all antiquity. In times when mathematical notation was in itself a new idea many used their own notation. The second book of the Sphaerica describes the application of spherical geometry to astronomical phenomena and is of little mathematical interest.

Note that this ratio does not depend on size of the particular right triangle chosen, as long as it contains the angle A, since all such triangles are similar.

Cavalieri used Ta and Ta. The Rhind papyrusan Egyptian collection of 84 problems in arithmeticalgebra, and geometry dating from about bce, contains five problems dealing with the seked. If an argument to sine or cosine in radians is scaled by frequency, then the derivatives will scale by amplitude. This is a common situation occurring in triangulation, a technique to determine unknown distances by measuring two angles and an accessible enclosed distance. Trigonometric functions in the complex plane Definitions via differential equations Both the sine and cosine functions satisfy the differential equation: Slope definitions Equivalent to the right-triangle definitions, the trigonometric functions can also be defined in terms of the rise, run, and slope of a line segment relative to horizontal.

On Triangles was greatly admired by future generations of scientists; the astronomer Nicolaus Copernicus — studied it thoroughly, and his annotated copy survives. Therefore to define an inverse function we must restrict their domains so that the trigonometric function is bijective.

Mnemonics[ edit ] Equivalent to the right-triangle definitions, the trigonometric functions can also be defined in terms of the rise, run, and slope of a line segment relative to horizontal. Cotangent From a theorem in complex analysis, there is a unique analytic continuation of this real function to the domain of complex numbers.

Theorems on the lengths of chords are essentially applications of the modern law of sines. Trigonometry (from Greek trigōnon, "triangle" and metron, "measure") is a branch of mathematics that studies relationships involving lengths and angles of elleandrblog.com field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies.

The 3rd-century astronomers first noted that the lengths of the sides of a right-angle triangle and the. Learn about the definition of the basic trigonometric functions (sin(x), cos(x), and tan(x)), and use advanced trigonometric functions for various purposes. History of Trigonometry The first trigonometric table was apparently compiled by Hipparchus, who is. The functions (also called the circular functions) comprising trigonometry: the cosecant cscx, cosine cosx, cotangent cotx, secant secx, sine sinx, and tangent tanx.

However, other notations are sometimes used, as summarized in the following table. f(x) alternate notations cotx ctnx (Erdélyi et al.p. 7), ctgx (Gradshteyn and Ryzhikp. xxix) cscx cosecx (Gradshteyn and Ryzhik Trigonometry.

The study of angles and of the angular relationships of planar and three-dimensional figures is known as trigonometry.

The trigonometric functions (also called the circular functions) comprising trigonometry are the cosecant, cosine, cotangent, secant, sine, and elleandrblog.com inverses of these functions are denoted,,, elleandrblog.com that the notation here means inverse function.

Values of Quadrantal Angles When an angle lies along an axis, the values of the trigonometric functions are either 0, 1, -1, or undefined. When the value of a trigonometric function is undefined, it means that the ratio for that given function involved division by zero.

History of trigonometric functions
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Trigonometric functions