A trigonometric function giving the ratio of the side adjacent to a given angle to the hypotenuse.
Fr.: cosinus hyperbolique
A function, denoted cosh x, defined for all real values of x, by the relation: cosh x = (1/2) (ex + e-x).
Lambert's cosine law
qânun-e cosinus-e Lambert
Fr.: loi en cosinus de Lambert
The intensity of the light emanating in any given direction from a perfectly diffusing surface is proportional to the cosine of the angle between the direction and the normal to the surface. Also called → Lambert's law.
law of cosines
Fr.: loi des cosinus
An expression that for any triangle relates the length of a side to the cosine of the opposite angle and the lengths of the two other sides. If a, b, and c are the sides and A, B, and C are the corresponding opposites angles: a2 = b2 + c2 - 2bc cos A; b2 = c2 + a2 - 2ca cos B; c2 = a2 + b2 - 2ab cos C.