SEC
Math & Trig
Returns the secant of an angle (in radians). The secant is the reciprocal of cosine: 1/COS(x).
Translations
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FinnishSEC
Syntax
SEC(number)Arguments
numberAn angle in radians for which to find the secant.
Examples
=SEC(0)1
SEC(0) is always 1
=SEC(PI()/3)2
Secant of 60° equals 2
Tips & Best Practices
- •Available since Excel 2013
- •Returns #DIV/0! when COS(number) is 0 (e.g. π/2, 3π/2)
- •Use RADIANS() to convert degrees to radians first
Common Mistakes
- •Passing an angle where cosine equals 0 (like π/2 or 3π/2), which returns a #DIV/0! error since secant is the reciprocal of cosine and undefined wherever cosine is 0
- •Passing an angle in degrees directly to SEC without converting it first - SEC expects radians, so SEC(60) doesn't give the secant of 60 degrees, and RADIANS(60) needs to be used instead
- •Confusing SEC with SIN or assuming it's some kind of alternate sine function - secant is specifically the reciprocal of cosine, unrelated to sine except through the broader trigonometric identities
Related Functions
COSCalculates the cosine of an angle, the reciprocal relationship to what SEC calculates (SEC(x) = 1/COS(x)).CSCCalculates the cosecant, the reciprocal of sine, a parallel function to SEC's reciprocal-of-cosine relationship.RADIANSConverts a degree value into radians, the unit SEC expects for its angle argument.Frequently Asked Questions
Why does SEC return a #DIV/0! error?
The angle is one where cosine equals 0, like π/2 or 3π/2 - since secant is 1/COS(x), dividing by that zero produces the error.
Why do I need RADIANS before using SEC?
SEC expects its input in radians, not degrees. If your angle is in degrees, wrap it in RADIANS first, like SEC(RADIANS(60)).
Is secant related to sine?
Not directly - secant is the reciprocal of cosine specifically. Cosecant (CSC) is the reciprocal of sine, a separate but parallel function.
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