A function of an angle expressed as the ratio of two of the sides of a right triangle that contains that angle; the sine, cosine, tangent, cotangent, secant, or cosecant. Also called circular function .
In a right triangle, the three main trigonometric functions are
sine &thgr; = opposite / hypotenuse
cosine &thgr; = adjacent / hypotenuse
tangent &thgr; = opposite / adjacent.
(plural trigonometric functions)
- (trigonometry) Any function of an angle expressed as the ratio of two of the sides of a right triangle that has that angle, or various other functions that subtract 1 from this value or subtract this value from 1 (such as the versed sine)