The Excel COT function returns the cotangent of an angle — the reciprocal of the tangent, 1/TAN. Excel measures angles in radians, so convert degrees with RADIANS first.
Syntax
| Argument | Description | |
|---|---|---|
number | Required | The angle in radians whose cotangent you want. Convert degrees with RADIANS(deg) or deg*PI()/180. |
How to use it
COT is simply 1/TAN(number), equal to COS divided by SIN. It was added in Excel 2013. Excel expects radians, so wrap any degree value in RADIANS():
Because cotangent is the reciprocal of tangent, =COT(x) gives the same result as =1/TAN(x) — useful in older versions without COT.
Undefined where tangent is zero. At 0° (and 180°) the tangent is zero, so cotangent is undefined and =COT(0) returns a #DIV/0! error. Use angles where tangent is non-zero.
Try it: interactive demo
Pick a COT example to see the formula and its result.
Practice workbook
Frequently asked questions
What is the cotangent of an angle?
COT(x) = 1/TAN(x), also equal to COS(x)/SIN(x).Which Excel versions have COT?
=1/TAN(x) instead.Why does COT(0) return an error?
=COT(0) returns #DIV/0!. Cotangent only works where tangent is non-zero.Does COT take degrees or radians?
RADIANS(deg), for example =COT(RADIANS(45)).Master functions like this in one day
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