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.
How to copy an example
- Create a blank workbook or worksheet.
- Select the example in the Help topic.
Note Do not select the row or column headers.
Selecting an example from Help
- Press CTRL+C.
- In the worksheet, select cell A1, and press CTRL+V.
- 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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| A |
B |
| 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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