# cosine

co·sine the reciprocal of the secant; specif.

- the ratio of the adjacent side of a given acute angle in a right triangle to the hypotenuse
- an equivalent, positive or negative ratio for certain related angles (Ex.: the cosine of 57° or 303° is .5446, of 123° or 237° is ?.5446) or real numbers representing radians (Ex.: cosine of .9948 radians (57°) is .5446)

Origin of cosine

Modern Latin from*co. sinus,*short for

*complementi sinus,*literally , sine of the complement

## cosine

noun

*Abbr.*

**cos**

- In a right triangle, the ratio of the length of the side adjacent to an acute angle to the length of the hypotenuse.
- The abscissa at 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.

**cosine**

cos &thgr; = ^{ b }_{ c }

## cosine

Noun

(*plural* cosines)

Usage notes

In various branches of mathematics, the cosine of an angle is determined in various ways, including the following:

## cosine - Computer Definition

See sine.