# cosine

Trigonometry.

(in a right triangle) the ratio of the side adjacent to a given angle to the hypotenuse.

the sine of the complement of a given angle or arc. Abbreviation: cos

Mathematics. (of a real or complex number x) the function cos x defined by the infinite series 1 − (x2/2!) + (x4/4!) − + …, where ! denotes factorial. Abbreviation: cos: Compare sine (def. 3), factorial (def. 1).

## Origin of cosine

^{1}

## Words Nearby cosine

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

## How to use cosine in a sentence

Thanks to the exponent on the

*cosine*function, this function does some strange things when N is less than 1.The variables do not literally represent the angle measurements themselves, but instead stand in for complex numbers associated to the cosines of the angles.

Tetrahedron Solutions Finally Proved Decades After Computer Search | Kevin Hartnett | February 2, 2021 | Quanta MagazineAnd, seating himself beside Dirrik, he began to explain the mysteries of sine,

*cosine*and tangent.Dry Fish and Wet | Anthon Bernhard Elias NilsenThe sine and the

*cosine*I shall have occasion to employ in the latter part of my lecture.Like the functions sine and

*cosine*, the elliptic functions have addition theorems, e.g.The New Gresham Encyclopedia | Various

Nevertheless, I bear no grudge against the sine and the

*cosine*, which I continue to hold in high esteem.The Life of the Fly | J. Henri FabreThe nine

*cosine*-inclinations above are, as has been seen, connected by six equations.

## British Dictionary definitions for cosine

/ (ˈkəʊˌsaɪn) /

a trigonometric function that in a right-angled triangle is the ratio of the length of the adjacent side to that of the hypotenuse; the sine of the complement: Abbreviation: cos

## Origin of cosine

^{1}

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

## Scientific definitions for cosine

[ kō′sīn′ ]

The ratio of the length of the side adjacent to an acute angle of a right triangle to the length of the hypotenuse.

The abscissa of the endpoint of an arc of a unit circle centered at the origin of a Cartesian coordinate system, the arc being of length x and measured counterclockwise from the point (1, 0) if x is positive or clockwise if x is negative.

A function of a number x, equal to the cosine of an angle whose measure in radians is equal to x.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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