cosine

American  

[koh-sahyn] / ˈkoʊ saɪn /

noun

1. Trigonometry.

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

   2. the sine of the complement of a given angle or arc. cos

2. Mathematics.  (of a real or complex numberx ) the function cos x defined by the infinite series 1 − (x 2 /2!) + (x 4 /4!) − + …, where ! denotes factorial. cos

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cosine British  

/ ˈkəʊˌsaɪn /

noun

1.  cos.  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

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cosine Scientific  

/ kō′sīn′ /

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

2. 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.

3. 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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Etymology

Origin of cosine

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

Example Sentences

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From Scientific American

These functions, such as the sine and cosine, are defined using right triangles.

From Scientific American

The mnemonic SO-CAH-TOA is commonly used to teach trigonometric functions sine, cosine and tangent.

From Washington Times

He proposed that all periodic functions — all periodic phenomena — could be understood as sums of sine and cosine waves.

From New York Times

And not once in the 40 years since I finished school have I ever been asked to factor a polynomial or calculate the cosine of anything.

From Los Angeles Times