# Tangent

noun
• trigonometry
the function that returns tangent of an angle.
• geometry
(of a plane or line) touching a curve or surface at only one point.
"The line is tangent to the circle at point A."

## Description

In math, the term “tangent” is used in both trigonometry and geometry. In trigonometry, tangent is one of the primary trigonometric functions. In geometry, a tangent refers to a straight line or plane that touches a curve at a single point without crossing through it at that point.

## Related Terms

A right triangle (or right-angled triangle) is a triangle in which one of the angles is a right angle (90 degrees). The side opposite the right angle is called the hypotenuse, and it is the longest side. The other two sides are known as the adjacent and opposite sides, relative to the non-right angle being referenced.

An angle is a measure of rotation or turning and is usually measured in degrees or radians. In geometry, an angle is the figure formed by two rays, sharing a common endpoint called the vertex.