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Returns the arccosine, or inverse cosine, of a number. The arccosine is the angle whose cosine is number. The returned angle is given in radians in the range 0 (zero) to pi.

## Syntax

ACOS(number)

Number     is the cosine of the angle you want and must be from -1 to 1.

## Remark

If you want to convert the result from radians to degrees, multiply it by 180/PI() or use the DEGREES function.

## Examples

Formula

Description (Result)

=ACOS(-0.5)

Arccosine of -0.5 in radians, 2*pi/3 (2.094395)

=ACOS(-0.5)*180/PI()

Arccosine of -0.5 in degrees (120)

=DEGREES(ACOS(-0.5))

Arccosine of -0.5 in degrees (120)

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