Sec-1

Sec-1, SEC-1, sec-1, or sec⁻¹ may refer to:

• sec x−1 = sec(x)−1 = exsec(x) or exsecant of x, an old trigonometric function
• sec⁻¹y = sec⁻¹(y), sometimes interpreted as arcsec(y) or arcsecant of y, the compositional inverse of the trigonometric function secant (see below for ambiguity)
• sec⁻¹x = sec⁻¹(x), sometimes interpreted as (sec(x))⁻¹ = 1/sec(x) = cos(x) or cosine of x, the multiplicative inverse (or reciprocal) of the trigonometric function secant (see above for ambiguity)
• sec x⁻¹, sometimes interpreted as sec(x⁻¹) = sec(1/x), the secant of the multiplicative inverse (or reciprocal) of x (see below for ambiguity)
• sec x⁻¹, sometimes interpreted as (sec(x))⁻¹ = 1/sec(x) = cos(x) or cosine of x, the multiplicative inverse (or reciprocal) of the trigonometric function secant (see above for ambiguity)