ACOS function

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.

Example

The example may be easier to understand if you copy it to a blank worksheet.

ShowHow to copy an example

  1. Create a blank workbook or worksheet.
  2. Select the example in the Help topic.

 Note   Do not select the row or column headers.

Selecting an example from Help

Selecting an example from Help
  1. Press CTRL+C.
  2. In the worksheet, select cell A1, and press CTRL+V.
  3. To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.
 
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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)
 
 
Applies to:
Excel 2007