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⁻¹y = 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⁻¹x = 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)