余切
Cotangent \Co*tan"gent\ (k?-t?n"jent), n. [For co. tangens, an abbrev. of L. complementi tangens. See {Tangent}.] (Trig.) The tangent of the complement of an arc or angle. See Illust. of {Functions}.
cotangent n : ratio of the adjacent to the opposite side of a right-angled triangle [syn: {cotan}]