Cos-1
# Cos-1

Cos-1, COS-1, cos-1, or $cos^{−1}$ may refer to:

* Cos-1, one of two commonly used COS cell lines
* cos x−1 = cos(x)−1 = −(1−cos(x)) = −ver(x) or negative versine of x, the additive inverse (or negation) of an old trigonometric function
* $cos^{−1}y$ = $cos^{−1}(y),$ sometimes interpreted as arccos(y) or arccosine of y, the compositional inverse of the trigonometric function cosine (see below for ambiguity)
* $cos^{−1}x$ = $cos^{−1}(x),$ sometimes interpreted as $(cos(x))^{−1}$ = 1/cos(x) = sec(x) or secant of x, the multiplicative inverse (or reciprocal) of the trigonometric function cosine (see above for ambiguity)
* cos $x^{−1},$ sometimes interpreted as $cos(x^{−1})$ = cos(1/x), the cosine of the multiplicative inverse (or reciprocal) of x (see below for ambiguity)
* cos $x^{−1},$ sometimes interpreted as $(cos(x))^{−1}$ = 1/cos(x) = sec(x) or secant of x, the multiplicative inverse (or reciprocal) of the trigonometric function cosine (see above for ambiguity)
