title: Cos-1
text: # 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)
  