Tan-1
# Tan-1

Tan-1, TAN-1, tan-1, or $tan^{−1}$ may refer to:

* $tan^{−1}y$ = $tan^{−1}(x),$ sometimes interpreted as arctan(x) or arctangent of x, the compositional inverse of the trigonometric function tangent (see below for ambiguity)
* $tan^{−1}x$ = $tan^{−1}(x),$ sometimes interpreted as $(tan(x))^{−1}$ = 1/tan(x) = cot(x) or cotangent of x, the multiplicative inverse (or reciprocal) of the trigonometric function tangent (see above for ambiguity)
* tan $x^{−1},$ sometimes interpreted as $tan(x^{−1})$ = tan(1/x), the tangent of the multiplicative inverse (or reciprocal) of x (see below for ambiguity)
* tan $x^{−1},$ sometimes interpreted as $(tan(x))^{−1}$ = 1/tan(x) = cot(x) or cotangent of x, the multiplicative inverse (or reciprocal) of the trigonometric function tangent (see above for ambiguity)

Because of ambiguity, the notation arctan(x) or $(tan(x))^{−1},$ is recommended.

