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
Word origin
C17: from New Latin cosinus; see co-, sine1
cosine in American English
(ˈkoʊˌsaɪn)
noun TrigonometryMathematics
the reciprocal of the secant
; specif.
a.
the ratio of the adjacent side of a given acute angle in a right triangle to the hypotenuse
b.
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)
Word origin
ModL < co. sinus, short for complementi sinus, lit., sine of the complement