cosine

American  

[koh-sahyn] / ˈkoʊ saɪn /

noun

cosines plural

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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Other Word Forms

Noun Inflected Forms

• cosines
  plural

Etymology

Origin of cosine

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

Example Sentences

See Examples For:

cosine cosines

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From Scientific American ● Aug. 17, 2023

The cosine of this angle is the length of the horizontal side divided by the hypotenuse.

From Scientific American ● Apr. 10, 2023

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

From Scientific American ● Apr. 10, 2023

This tells us that 150° has the same sine and cosine values as 30°, except for the sign.

From Textbooks ● Dec. 1, 2021

The misery began when I moved beyond the Pythagorean theorem to sine, cosine and tangent.

From "Educated" by Tara Westover

This vector is a unit vector, and the components of the unit vector are called directional cosines.

From Textbooks ● Mar. 30, 2016

Determine the direction cosines of vector u = i + 2j + 2k and show they satisfy cos2 α + cos2 β + cos2 γ = 1.

From Textbooks ● Mar. 30, 2016

The law of cosines can be thought of as a function of three variables.

From Textbooks ● Mar. 30, 2016

The cosines of these angles are known as the direction cosines.

From Textbooks ● Mar. 30, 2016

She smoked and talked and ate for an hour without stopping, and I scribbled in my notebook as the muddy waters of tangents and cosines began to clarify.

From "Looking for Alaska" by John Green