function, mathematical function - a mathematical relation such that each element of one set is associated with at least one element of another set

sine, sin - ratio of the opposite side to the hypotenuse of a right-angled triangle

cos, cosine - ratio of the adjacent side to the hypotenuse of a right-angled triangle

tangent, tan - ratio of the opposite to the adjacent side of a right-angled triangle

cotan, cotangent - ratio of the adjacent to the opposite side of a right-angled triangle

sec, secant - ratio of the hypotenuse to the adjacent side of a right-angled triangle

cosec, cosecant - ratio of the hypotenuse to the opposite side of a right-angled triangle