ACOT
Returns the principal value of the arccotangent (inverse cotangent) of a number, in radians, in the range 0 to π.
ACOT(number)Arguments
numberAny real number.
=ACOT(1)Arccotangent of 1 (= π/4)
=ACOT(0)Arccotangent of 0 (= π/2)
- •Available since Excel 2013
- •Result is always between 0 and π (in radians)
- •Use DEGREES(ACOT(x)) to convert the result to degrees
- •Expecting ACOT(0) to be undefined or produce an error - it's actually perfectly valid and returns π/2, since the arccotangent function is defined across the entire real number line
- •Confusing ACOT with ATAN by assuming ACOT(x) always equals 1/ATAN(x) - the actual mathematical relationship between arccotangent and arctangent is more nuanced and doesn't reduce to a simple reciprocal
- •Expecting a result in degrees - ACOT always returns radians, so DEGREES() needs to be applied separately for a degree-based angle
COTPerforms the inverse operation - calculates the cotangent of an angle, undoing what ACOT calculates.ATANCalculates the arctangent, a closely related inverse trigonometric function with a different output range than ACOT.DEGREESConverts ACOT's radian result into degrees, a common step since ACOT never returns degrees directly.Why doesn't ACOT(0) produce an error?
Unlike some other trigonometric functions with restricted domains, arccotangent is defined for every real number, including 0 - ACOT(0) correctly returns π/2.
Is ACOT(x) the same as 1/ATAN(x)?
No, that's a common misconception - the actual relationship between arccotangent and arctangent is more specific than a simple reciprocal, and computing it that way can give incorrect results.
What range of values can ACOT return?
Always between 0 and π radians, regardless of the sign or magnitude of the input number.
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