Abk. tan, eine der Winkelfunktionen.
ETYM Latin tangens, -entis, p. pr. of tangere to touch.
1. A straight line that touches but does not intersect a curve.
2. Ratio of the opposite to the adjacent side.
In geometry, a straight line that touches a curve and gives the gradient of the curve at the point of contact. At a maximum, minimum, or point of inflection, the tangent to a curve has zero gradient. Also, in trigonometry, a function of an acute angle in a right triangle, defined as the ratio of the length of the side opposite the angle to the length of the side adjacent to it; a way of expressing the gradient of a line.