Math & Trig

ACOT Formula

ACOT returns the arccotangent of a number — the angle whose cotangent is the given value. The result is in radians, in the range 0 to π. It's the inverse of COT and is less commonly used than ATAN, but appears in certain engineering and mathematical formulas.

Syntax

ACOT(number)
ParameterDescription
number Parameter of the ACOT function.
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Examples

Arccotangent of 1

Formula
=ACOT(1)
Returns ~0.7854 (π/4 radians or 45°). The angle whose cotangent is 1 is 45°, same as ATAN(1).

Convert to degrees

Formula
=DEGREES(ACOT(2))
Returns ~26.57°. The angle whose cotangent is 2 is about 26.6 degrees.

Complement of ATAN

Formula
=DEGREES(ACOT(1)) + DEGREES(ATAN(1))
Returns 90. ACOT(x) + ATAN(x) = π/2 (90°) for any positive x. They are complementary functions.

Common Errors

#VALUE!

Non-numeric input returns #VALUE!. ACOT accepts any real number.

Tips

Relationship to ATAN

ACOT(x) = π/2 - ATAN(x) for positive x. If you know how to use ATAN, you can always compute ACOT from it.

Range is 0 to π

ACOT returns values from 0 to π (0° to 180°), never negative. This is different from ATAN which returns -π/2 to π/2.

Accepts any number

Like ATAN, ACOT accepts any real number. There are no domain restrictions (unlike ASIN/ACOS which require -1 to 1).

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