cosine

[ koh-sahyn ]

noun

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

1625–35; <New Latin cosinus. See co-, sine

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.
Can You Prime The Cube? | Zach Wissner-Gross | February 11, 2022 | FiveThirtyEight
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 Magazine
And, seating himself beside Dirrik, he began to explain the mysteries of sine, cosine and tangent.
Dry Fish and Wet | Anthon Bernhard Elias Nilsen
The sine and the cosine I shall have occasion to employ in the latter part of my lecture.
Scientific American Supplement, Vol. XXI., No. 531, March 6, 1886 | Various
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 Fabre
The nine cosine-inclinations above are, as has been seen, connected by six equations.
Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 6 | Various

British Dictionary definitions for cosine

cosine

/ (ˈkəʊˌsaɪn) /

noun(of an angle)

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

C17: from New Latin cosinus; see co-, sine 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

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.

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