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Acos

ACOS Function

The ACOS function in Excel returns the arccosine (or inverse cosine) of a number. The result, in radians, is between 0 and π. Essentially, it's the angle whose cosine is the specified number.

Syntax:

ACOS(number)
  • number: This is a required argument. It must be a numeric value between -1 and 1 (inclusive).

Examples:

  1. =ACOS(0.5) would return an angle in radians, approximately 1.0472 (or 60° when converted to degrees).
  2. =ACOS(-1) would return π (approximately 3.1416 radians, or 180°).
  3. =ACOS(A1) would return the arccosine of the number in cell A1, provided the value in A1 is within the valid range.

Note: If you want the result in degrees instead of radians, you can use the formula =DEGREES(ACOS(number)).